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APA Format for Students & Researchers

In this guide, students and researchers can learn the basics of creating a properly formatted research paper according to APA guidelines.

It includes information on how to conceptualize, outline, and format the basic structure of your paper, as well as practical tips on spelling, abbreviation, punctuation, and more. The guide concludes with a complete sample paper as well as a final checklist that writers can use to prepare their work for submission.

APA Paper Formatting Basics

• All text should be double-spaced
• Use one-inch margins on all sides
• All paragraphs in the body are indented
• Make sure that the title is centered on the page with your name and school/institution underneath
• Use 12-point font throughout
• All pages should be numbered in the upper right hand corner
• The manual recommends using one space after most punctuation marks
• A shortened version of the title (“running head”) should be placed in the upper left hand corner

Table of Contents

Here’s a quick rundown of the contents of this guide on how to do APA format.

Information related to writing and organizing your paper:

• Paper and essay categories

General paper length

• Margin sizes
• Title pages
• Running Heads
• APA Outline
• APA Abstract
• The body of papers
• APA headings and subheadings
• Use of graphics (tables and figures)

Writing style tips:

Proper tone.

• Reducing bias and labels
• Abbreviation do’s and don’ts
• Punctuation
• Number rules

Citing Your Sources:

• Citing Sources
• In-text Citations
• Reference Page

Proofing Your Paper:

• Final checklist
• Submitting your project

APA Information:

• What is APA
• APA 7 Updates

What you won’t find in this guide: This guide provides information related to the formatting of your paper, as in guidelines related to spacing, margins, word choice, etc. While it provides a general overview of APA references, it does not provide instructions for how to cite in APA format.

For step-by-step instructions for citing books, journals, how to cite a website in APA format, information on an APA format bibliography, and more, refer to these other EasyBib guides:

• APA citation (general reference guide)
• APA In-text citation
• APA article citation
• APA book citation
• APA citation website

Or, you can use our automatic generator. Our APA formatter helps to build your references for you. Yep, you read that correctly.

Writing and Organizing Your APA Paper in an Effective Way

This section of our guide focuses on proper paper length, how to format headings, spacing, and more! This information can be found in Chapter 2 of the official manual (American Psychological Association, 2020, pp. 29-67).

Categories of papers

Before getting into the nitty-gritty details related to APA research paper format, first determine the type of paper you’re about to embark on creating:

Empirical studies

Empirical studies take data from observations and experiments to generate research reports. It is different from other types of studies in that it isn’t based on theories or ideas, but on actual data.

Literature reviews

These papers analyze another individual’s work or a group of works. The purpose is to gather information about a current issue or problem and to communicate where we are today. It sheds light on issues and attempts to fill those gaps with suggestions for future research and methods.

Theoretical articles

These papers are somewhat similar to a literature reviews in that the author collects, examines, and shares information about a current issue or problem, by using others’ research. It is different from literature reviews in that it attempts to explain or solve a problem by coming up with a new theory. This theory is justified with valid evidence.

Methodological articles

These articles showcase new advances, or modifications to an existing practice, in a scientific method or procedure. The author has data or documentation to prove that their new method, or improvement to a method, is valid. Plenty of evidence is included in this type of article. In addition, the author explains the current method being used in addition to their own findings, in order to allow the reader to understand and modify their own current practices.

Case studies

Case studies present information related an individual, group, or larger set of individuals. These subjects are analyzed for a specific reason and the author reports on the method and conclusions from their study. The author may also make suggestions for future research, create possible theories, and/or determine a solution to a problem.

Since APA style format is used often in science fields, the belief is “less is more.” Make sure you’re able to get your points across in a clear and brief way. Be direct, clear, and professional. Try not to add fluff and unnecessary details into your paper or writing.  This will keep the paper length shorter and more concise.

Margin sizes in APA Format

When it comes to margins, keep them consistent across the left, right, top, and bottom of the page. All four sides should be the same distance from the edge of the paper. It’s recommended to use at least one-inch margins around each side. It’s acceptable to use larger margins, but the margins should never be smaller than an inch.

Title pages in APA Format

The title page, or APA format cover page, is the first page of a paper or essay. Some teachers and professors do not require a title page, but some do. If you’re not sure if you should include one or not, ask your teacher. Some appreciate the page, which clearly displays the writer’s name and the title of the paper.

The APA format title page for student papers includes six main components:

• the title of the APA format paper
• names of all authors
• institutional affiliation
• course number and title
• instructor’s name

Title pages for professional papers  also require a running head; student papers do not.

Some instructors and professional publications also ask for an author’s note. If you’re required or would like to include an author’s note, place it below the institutional affiliation. Examples of information included in an author’s note include an ORCID iD number, a disclosure, and an acknowledgement.

Here are key guidelines to developing your title page:

• The title of the paper should capture the main idea of the essay, but should not contain abbreviations or words that serve no purpose. For example, instead of using the title “A Look at Amphibians From the Past,” title the paper “Amphibians From the Past.” Delete the unnecessary fluff!
• Center the title on the page and place it about 3-4 lines from the top.
• The title should be bolded, in title case, and the same font size as your other page text. Do not underline or italicize the title. Other text on the page should be plain (not bolded , underlined, or italicized ). 
• All text on the title page should be double-spaced. The APA format examples paper below displays proper spacing, so go take a look!
• Do not include any titles in the author’s name such as Dr. or Ms. In contrast, for your instructor’s name, use the form they prefer (e.g., Sagar Parekh, PhD; Dr. Minako Asato; Professor Nathan Ian Brown; etc.).
• The institutional affiliation is the school the author attends or the location where the author conducted the research.

In a hurry? Try the  EasyBib title page maker to easily create a title page for free.

Sample of an APA format title page for a student paper:

Sample of title page for a professional paper:

Running heads in APA Format

The 7th edition of the American Psychological Association Publication Manual (p. 37) states that running heads are not required for student papers unless requested by the instructor. Student papers still need a page number included in the upper right-hand corner of every page. The 6th edition required a running head for student papers, so be sure to confirm with your instructor which edition you should follow. Of note, this guide follows the 7th edition.

Running heads are required for professional papers (e.g., manuscripts submitted for publication). Read on for instructions on how to create them.

Are you wondering what is a “running head”? It’s basically a page header at the top of every page. To make this process easier, set your word processor to automatically add these components onto each page. You may want to look for “Header” in the features.

A running head/page header includes two pieces:

• the title of the paper
• page numbers.

Insert page numbers justified to the right-hand side of the APA format paper (do not put p. or pg. in front of the page numbers).

For all pages of the paper, including the APA format title page, include the “TITLE OF YOUR PAPER” justified to the left in capital letters (i.e., the running head). If your full title is long (over 50 characters), the running head title should be a shortened version.

Preparing outlines in APA Format

Outlines are extremely beneficial as they help writers stay organized, determine the scope of the research that needs to be included, and establish headings and subheadings.

There isn’t an official or recommended “APA format for outline” structure. It is up to the writer (if they choose to make use of an outline) to determine how to organize it and the characters to include. Some writers use a mix of roman numerals, numbers, and uppercase and lowercase letters.

Even though there isn’t a required or recommended APA format for an outline, we encourage writers to make use of one. Who wouldn’t want to put together a rough outline of their project? We promise you, an outline will help you stay on track.

Here’s our version of how APA format for outlines could look:

Don’t forget, if you’re looking for information on APA citation format and other related topics, check out our other comprehensive guides.

How to form an abstract in APA

An APA format abstract (p. 38) is a summary of a scholarly article or scientific study. Scholarly articles and studies are rather lengthy documents, and abstracts allow readers to first determine if they’d like to read an article in its entirety or not.

You may come across abstracts while researching a topic. Many databases display abstracts in the search results and often display them before showing the full text of an article or scientific study. It is important to create a high quality abstract that accurately communicates the purpose and goal of your paper, as readers will determine if it is worthy to continue reading or not.

Are you wondering if you need to create an abstract for your assignment? Usually, student papers do not require an abstract. Abstracts are not typically seen in class assignments, and are usually only included when submitting a paper for publication. Unless your teacher or professor asked for it, you probably don’t need to have one for your class assignment.

If you’re planning on submitting your paper to a journal for publication, first check the journal’s website to learn about abstract and APA paper format requirements.

Here are some helpful suggestions to create a dynamic abstract:

• Abstracts are found on their own page, directly after the title or cover page.
• Professional papers only (not student papers): Include the running head on the top of the page.
• On the first line of the page, center the word “Abstract” (but do not include quotation marks).
• On the following line, write a summary of the key points of your research. Your abstract summary is a way to introduce readers to your research topic, the questions that will be answered, the process you took, and any findings or conclusions you drew. Use concise, brief, informative language. You only have a few sentences to share the summary of your entire document, so be direct with your wording.
• This summary should not be indented, but should be double-spaced and less than 250 words.
• If applicable, help researchers find your work in databases by listing keywords from your paper after your summary. To do this, indent and type Keywords : in italics.  Then list your keywords that stand out in your research. You can also include keyword strings that you think readers will type into the search box.
• Active voice: The subjects reacted to the medication.
• Passive voice: There was a reaction from the subjects taking the medication.
• Instead of evaluating your project in the abstract, simply report what it contains.
• If a large portion of your work includes the extension of someone else’s research, share this in the abstract and include the author’s last name and the year their work was released.

APA format example page:

Here’s an example of an abstract:

Visual design is a critical aspect of any web page or user interface, and its impact on a user’s experience has been studied extensively. Research has shown a positive correlation between a user’s perceived usability and a user’s assessment of visual design. Additionally, perceived web quality, which encompasses visual design, has a positive relationship with both initial and continued consumer purchase intention. However, visual design is often assessed using self-report scale, which are vulnerable to a few pitfalls. Because self-report questionnaires are often reliant on introspection and honesty, it is difficult to confidently rely on self-report questionnaires to make important decisions. This study aims to ensure the validity of a visual design assessment instrument (Visual Aesthetics of Websites Inventory: Short version) by examining its relationship with biometric (variables), like galvanic skin response, pupillometry, and fixation information. Our study looked at participants assessment of a webpage’s visual design, and compared it to their biometric responses while viewing the webpage. Overall, we found that both average fixation duration and pupil dilation differed when participants viewed web pages with lower visual design ratings compared to web pages with a higher visual design rating.

Keywords : usability, visual design, websites, eye tracking, pupillometry, self-report, VisAWI

The body of an APA paper

On the page after the title page (if a student paper) or the abstract (if a professional paper), begin with the body of the paper.

Most papers follow this format:

• At the top of the page, add the page number in the upper right corner of all pages, including the title page.
• On the next line write the title in bold font and center it. Do not underline or italicize it.
• Begin with the introduction and indent the first line of the paragraph. All paragraphs in the body are indented.

Sample body for a student paper:

Most scientific or professional papers have additional sections and guidelines:

• Start with the running head (title + page number). The heading title should be in capital letters. The abstract page should be page 2.
• The introduction presents the problem and premise upon which the research was based. It goes into more detail about this problem than the abstract.
• Begin a new section with the Method and use this word as the subtitle. Bold and center this subtitle. The Method section shows how the study was run and conducted. Be sure to describe the methods through which data was collected.
• Begin a new section with the Results . Bold and center this subtitle. The Results section summarizes your data. Use charts and graphs to display this data.
• Draw conclusions and support how your data led to these conclusions.
• Discuss whether or not your hypothesis was confirmed or not supported by your results.
• Determine the limitations of the study and next steps to improve research for future studies.

Sample body for a professional paper:

Keep in mind, APA citation format is much easier than you think, thanks to EasyBib.com. Try our automatic generator and watch how we create APA citation format references for you in just a few clicks. While you’re at it, take a peek at our other helpful guides, such as our APA reference page guide, to make sure you’re on track with your research papers.

Proper usage of headings & subheadings in APA Format

Headings (p. 47) serve an important purpose in research papers — they organize your paper and make it simple to locate different pieces of information. In addition, headings provide readers with a glimpse to the main idea, or content, they are about to read.

In APA format, there are five levels of headings, each with a different formatting:

• This is the title of your paper
• The title should be centered in the middle of the page
• The title should be bolded
• Use uppercase and lowercase letters where necessary (called title capitalization)
• Place this heading against the left margin
• Use bold letters
• Use uppercase and lowercase letters where necessary
• Place this heading against the left side margin
• End the heading with a period
• Indented in from the left margin

Following general formatting rules, all headings are double spaced and there are no extra lines or spaces between sections.

Here is a visual APA format template for levels of headings:

Use of graphics (tables and figures) in APA Format

If you’re looking to jazz up your project with any charts, tables, drawings, or images, there are certain APA format rules (pp. 195-250) to follow.

First and foremost, the only reason why any graphics should be added is to provide the reader with an easier way to see or read information, rather than typing it all out in the text.

Lots of numbers to discuss? Try organizing your information into a chart or table. Pie charts, bar graphs, coordinate planes, and line graphs are just a few ways to show numerical data, relationships between numbers, and many other types of information.

Instead of typing out long, drawn out descriptions, create a drawing or image. Many visual learners would appreciate the ability to look at an image to make sense of information.

Before you go ahead and place that graphic in your paper, here are a few key guidelines:

• Follow them in the appropriate numerical order in which they appear in the text of your paper. Example : Figure 1, Figure 2, Table 1, Figure 3.
• Example: Figure 1, Figure 2, Table 1, Figure 3
• Only use graphics if they will supplement the material in your text. If they reinstate what you already have in your text, then it is not necessary to include a graphic.
• Include enough wording in the graphic so that the reader is able to understand its meaning, even if it is isolated from the corresponding text. However, do not go overboard with adding a ton of wording in your graphic.
• Left align tables and figures

In our APA format sample paper , you’ll find examples of tables after the references. You may also place tables and figures within the text just after it is mentioned.

Is there anything better than seeing a neatly organized data table? We think not! If you have tons of numbers or data to share, consider creating a table instead of typing out a wordy paragraph. Tables are pretty easy to whip up on Google Docs or Microsoft Word.

General format of a table should be:

• Table number
• Choose to type out your data OR create a table. As stated above, in APA format, you shouldn’t have the information typed out in your paper and also have a table showing the same exact information. Choose one or the other.
• If you choose to create a table, discuss it very briefly in the text. Say something along the lines of, “Table 1 displays the amount of money used towards fighting Malaria.” Or, “Stomach cancer rates are displayed in Table 4.”
• If you’re submitting your project for a class, place your table close to the text where it’s mentioned. If you’re submitting it to be published in a journal, most publishers prefer tables to be placed in the back. If you’re unsure where to place your tables, ask!
• Include the table number first and at the top. Table 1 is the first table discussed in the paper. Table 2 is the next table mentioned, and so on. This should be in bold.
• Add a title under the number. Create a brief, descriptive title. Capitalize the first letter for each important word. Italicize the title and place it under the table number.
• Only use horizontal lines.
• Limit use of cell shading.
• Keep the font at 12-point size and use single or double spacing. If you use single spacing in one table, make sure all of the others use single spaces as well. Keep it consistent.
• All headings should be centered.
• In the first column (called the stub), center the heading, left-align the information underneath it (indent 0.15 inches if info is more than one line).
• Information in other columns should be centered.
• General . Information about the whole table.
• Specific . Information targeted for a specific column, row, or cell.
• Probability . Explains what certain table symbols mean. For example, asterisks,  p values, etc.

Here’s an APA format example of a table:

We know putting together a table is pretty tricky. That’s why we’ve included not one, but a few tables on this page. Scroll down and look at the additional tables in the essay in APA format example found below.

Figures represent information in a visual way. They differ from tables in that they are visually appealing. Sure, tables, like the one above, can be visually appealing, but it’s the color, circles, arrows, boxes, or icons included that make a figure a “figure.”

There are many commonly used figures in papers. Examples APA Format:

• Photographs
• Hierarchy charts

General format of a figure is the same as tables. This means each should include:

• Figure number

Use the same formatting tables use for the number, title, and note.

Here are some pointers to keep in mind when it comes to APA format for figures:

• Only include a figure if it adds value to your paper. If it will truly help with understanding, include it!
• Either include a figure OR write it all out in the text. Do not include the same information twice.
• If a note is added, it should clearly explain the content of the figure. Include any reference information if it’s reproduced or adapted.

APA format sample of a figure:

Photographs:

We live in a world where we have tons of photographs available at our fingertips.

Photographs found through Google Images, social media, stock photos made available from subscription sites, and tons of other various online sources make obtaining photographs a breeze. We can even pull out our cell phones, and in just a few seconds, take pictures with our cameras.

Photographs are simple to find, and because of this, many students enjoy using them in their papers.

If you have a photograph you would like to include in your project, here are some guidelines from the American Psychological Association.

• Create a reference for the photograph. Follow the guidelines under the table and figure sections above.
• Do not use color photos. It is recommended to use black and white. Colors can change depending on the reader’s screen resolution. Using black and white ensures the reader will be able to view the image clearly. The only time it is recommended to use color photos is if you’re writing about color-specific things. For example, if you’re discussing the various shades of leaf coloration, you may want to include a few photographs of colorful leaves.
• If there are sections of the photograph that are not related to your work, it is acceptable to crop them out. Cropping is also beneficial in that it helps the reader focus on the main item you’re discussing.
• If you choose to include an image of a person you know, it would be respectful if you ask their permission before automatically including their photo in your paper.  Some schools and universities post research papers online and some people prefer that their photos and information stay off the Internet.

B. Writing Style Tips

Writing a paper for scientific topics is much different than writing for English, literature, and other composition classes. Science papers are much more direct, clear, and concise. This section includes key suggestions, explains how to write in APA format, and includes other tidbits to keep in mind while formulating your research paper.

Verb usage in APA

Research experiments and observations rely on the creation and analysis of data to test hypotheses and come to conclusions. While sharing and explaining the methods and results of studies, science writers often use verbs.

When using verbs in writing, make sure that you continue to use them in the same tense throughout the section you’re writing. Further details are in the publication manual (p. 117).

Here’s an APA format example:

We tested the solution to identify the possible contaminants.

It wouldn’t make sense to add this sentence after the one above:

We tested the solution to identify the possible contaminants. Researchers often test solutions by placing them under a microscope.

Notice that the first sentence is in the past tense while the second sentence is in the present tense. This can be confusing for readers.

For verbs in scientific papers, the APA manual recommends using:

• Past tense or present perfect tense for the explantation of the procedure
• Past tense for the explanation of the results
• Present tense for the explanation of the conclusion and future implications

If this is all a bit much, and you’re simply looking for help with your references, try the EasyBib.com APA format generator . Our APA formatter creates your references in just a few clicks. APA citation format is easier than you think thanks to our innovative, automatic tool.

Even though your writing will not have the same fluff and detail as other forms of writing, it should not be boring or dull to read. The Publication Manual suggests thinking about who will be the main reader of your work and to write in a way that educates them.

How to reduce bias & labels

The American Psychological Association strongly objects to any bias towards gender, racial groups, ages of individuals or subjects, disabilities, and sexual orientation (pp. 131-149). If you’re unsure whether your writing is free of bias and labels or not, have a few individuals read your work to determine if it’s acceptable.

Here are a few guidelines that the American Psychological Association suggests :

• Only include information about an individual’s orientation or characteristic if it is important to the topic or study. Do not include information about individuals or labels if it is not necessary.
• If writing about an individual’s characteristic or orientation, for essay APA format, make sure to put the person first. Instead of saying, “Diabetic patients,” say, “Patients who are diabetic.”
• Instead of using narrow terms such as, “adolescents,” or “the elderly,” try to use broader terms such as, “participants,” and “subjects.”
• “They” or “their” are acceptable gender-neutral pronouns to use.
• Be mindful when using terms that end with “man” or “men” if they involve subjects who are female. For example, instead of using “Firemen,” use the term, “Firefighter.” In general, avoid ambiguity.
• When referring to someone’s racial or ethnic identity, use the census category terms and capitalize the first letter. Also, avoid using the word, “minority,” as it can be interpreted as meaning less than or deficient. Instead, say “people of color” or “underrepresented groups.”
• When describing subjects in APA format, use the words “girls” and “boys” for children who are under the age of 12. The terms, “young woman,” “young man,” “female adolescent,” and “male adolescent” are appropriate for subjects between 13-17 years old; “Men,” and “women,” for those older than 18. Use the term, “older adults.” for individuals who are older. “Elderly,” and “senior,” are not acceptable if used only as nouns. It is acceptable to use these terms if they’re used as adjectives.

Read through our example essay in APA format, found in section D, to see how we’ve reduced bias and labels.

Spelling in APA Format

• In APA formatting, use the same spelling as words found in Merriam-Webster’s Collegiate Dictionary (American English) (p. 161).
• If the word you’re trying to spell is not found in Webster’s Collegiate Dictionary, a second resource is Webster’s Third New International Dictionary .
• If attempting to properly spell words in the psychology field, consult the American Psychological Association’s Dictionary of Psychology

Thanks to helpful tools and features, such as the spell checker, in word processing programs, most of us think we have everything we need right in our document. However, quite a few helpful features are found elsewhere.

Where can you find a full grammar editor? Right here, on EasyBib.com. The EasyBib Plus paper checker scans your paper for spelling, but also for any conjunction , determiner, or adverb out of place. Try it out and unlock the magic of an edited paper.

Abbreviation do’s and don’ts in APA Format

Abbreviations can be tricky. You may be asking yourself, “Do I include periods between the letters?” “Are all letters capitalized?” “Do I need to write out the full name each and every time?” Not to worry, we’re breaking down the publication manual’s abbreviations (p. 172) for you here.

First and foremost, use abbreviations sparingly.

Too many and you’re left with a paper littered with capital letters mashed together. Plus, they don’t lend themselves to smooth and easy reading. Readers need to pause and comprehend the meaning of abbreviations and quite often stumble over them.

• If the abbreviation is used less than three times in the paper, type it out each time. It would be pretty difficult to remember what an abbreviation or acronym stands for if you’re writing a lengthy paper.
• If you decide to sprinkle in abbreviations,  it is not necessary to include periods between the letters.
• Example: While it may not affect a patient’s short-term memory (STM), it may affect their ability to comprehend new terms. Patients who experience STM loss while using the medication should discuss it with their doctor.
• Example : AIDS
• The weight in pounds exceeded what we previously thought.

Punctuation in APA Format

One space after most punctuation marks.

The manual recommends using one space after most punctuation marks, including punctuation at the end of a sentence (p. 154). It doesn’t hurt to double check with your teacher or professor to ask their preference since this rule was changed recently (in 2020).

The official APA format book was primarily created to aid individuals with submitting their paper for publication in a professional journal. Many schools adopt certain parts of the handbook and modify sections to match their preference. To see an example of an APA format research paper, with the spacing we believe is most commonly and acceptable to use, scroll down and see section D.

For more information related to the handbook, including frequently asked questions, and more, here’s further reading on the style

It’s often a heated debate among writers whether or not to use an Oxford comma (p. 155), but for this style, always use an Oxford comma. This type of comma is placed before the words AND and OR or in a series of three items.

Example of APA format for commas: The medication caused drowsiness, upset stomach, and fatigue.

Here’s another example: The subjects chose between cold, room temperature, or warm water.

Apostrophes

When writing a possessive singular noun, you should place the apostrophe before the s. For possessive plural nouns, the apostrophe is placed after the s.

• Singular : Linda Morris’s jacket
• Plural : The Morris’ house

Em dashes (long dash) are used to bring focus to a particular point or an aside. There are no spaces after these dashes (p. 157).

Use en dashes (short dash) in compound adjectives. Do not place a space before or after the dash. Here are a few examples:

• custom-built
• 12-year-old

Number rules in APA Format

Science papers often include the use of numbers, usually displayed in data, tables, and experiment information. The golden rule to keep in mind is that numbers less than 10 are written out in text. If the number is more than 10, use numerals.

APA format examples:

• 14 kilograms
• seven individuals
• 83 years old
• Fourth grade

The golden rule for numbers has exceptions.

In APA formatting, use numerals if you are:

• Showing numbers in a table or graph
• 4 divided by 2
• 6-month-olds

Use numbers written out as words if you are:

• Ninety-two percent of teachers feel as though….
• Hundred Years’ War
• One-sixth of the students

Other APA formatting number rules to keep in mind:

• World War II
• Super Bowl LII
• It’s 1980s, not 1980’s!

Additional number rules can be found in the publication manual (p. 178)

Need help with other writing topics? Our plagiarism checker is a great resource for anyone looking for writing help. Say goodbye to an out of place noun , preposition , or adjective, and hello to a fully edited paper.

Overview of APA references

While writing a research paper, it is always important to give credit and cite your sources; this lets you acknowledge others’ ideas and research you’ve used in your own work. Not doing so can be considered plagiarism , possibly leading to a failed grade or loss of a job.

APA style is one of the most commonly used citation styles used to prevent plagiarism. Here’s more on crediting sources . Let’s get this statement out of the way before you become confused: An APA format reference and an APA format citation are two different things! We understand that many teachers and professors use the terms as if they’re synonyms, but according to this specific style, they are two separate things, with different purposes, and styled differently.

A reference displays all of the information about the source — the title, the author’s name, the year it was published, the URL, all of it! References are placed on the final page of a research project.

Here’s an example of a reference:

Wynne-Jones, T. (2015). The emperor of any place . Candlewick Press.

An APA format citation is an APA format in-text citation. These are found within your paper, anytime a quote or paraphrase is included. They usually only include the name of the author and the date the source was published.

Here’s an example of one:

Hypertrophic cardiomyopathy is even discussed in the book, The Emperor of Any Place . The main character, Evan, finds a mysterious diary on his father’s desk (the same desk his father died on, after suffering from a hypertrophic cardiomyopathy attack). Evan unlocks the truth to his father and grandfather’s past (Wynne-Jones, 2015).

Both of the ways to credit another individual’s work — in the text of a paper and also on the final page — are key to preventing plagiarism. A writer must use both types in a paper. If you cite something in the text, it must have a full reference on the final page of the project. Where there is one, there must be the other!

Now that you understand that, here’s some basic info regarding APA format references (pp. 281-309).

• Each reference is organized, or structured, differently. It all depends on the source type. A book reference is structured one way, an APA journal is structured a different way, a newspaper article is another way. Yes, it’s probably frustrating that not all references are created equal and set up the same way. MLA works cited pages are unique in that every source type is formatted the same way. Unfortunately, this style is quite different.
• Most references follow this general format:

Author’s Last name, First initial. Middle initial. (Year published). Title of source . URL.

Again, as stated in the above paragraph, you must look up the specific source type you’re using to find out the placement of the title, author’s name, year published, etc.

For more information on APA format for sources and how to reference specific types of sources, use the other guides on EasyBib.com. Here’s another useful site .

Looking for a full visual of a page of references? Scroll down and take a peek at our APA format essay example towards the bottom of this page. You’ll see a list of references and you can gain a sense of how they look.

Bonus: here’s a link to more about the fundamentals related to this particular style. If you want to brush up or catch up on the Modern Language Association’s style, here’s a great resource on how to cite websites in MLA .

In-text APA citation format

Did you find the perfect quote or piece of information to include in your project? Way to go! It’s always a nice feeling when we find that magical piece of data or info to include in our writing. You probably already know that you can’t just copy and paste it into your project, or type it in, without also providing credit to the original author.

Displaying where the original information came from is much easier than you think.Directly next to the quote or information you included, place the author’s name and the year nearby. This allows the reader of your work to see where the information originated.

APA allows for the use of two different forms of in-text citation, parenthetical and narrative Both forms of citation require two elements:

• author’s name
• year of publication

The only difference is the way that this information is presented to the reader.

Parenthetical citations are the more commonly seen form of in-text citations for academic work, in which both required reference elements are presented at the end of the sentence in parentheses. Example:

Harlem had many artists and musicians in the late 1920s (Belafonte, 2008).

Narrative citations allow the author to present one or both of the required reference elements inside of the running sentence, which prevents the text from being too repetitive or burdensome. When only one of the two reference elements is included in the sentence, the other is provided parenthetically. Example:

According to Belafonte (2008), Harlem was full of artists and musicians in the late 1920s.

If there are two authors listed in the source entry, then the parenthetical reference must list them both:

(Smith & Belafonte, 2008)

If there are three or more authors listed in the source entry, then the parenthetical reference can abbreviate with “et al.”, the latin abbreviation for “and others”:

(Smith et al., 2008)

The author’s names are structured differently if there is more than one author. Things will also look different if there isn’t an author at all (which is sometimes the case with website pages). For more information on APA citation format, check out this page on the topic: APA parenthetical citation and APA in-text citation . There is also more information in the official manual in chapter 8.

If it’s MLA in-text and parenthetical citations you’re looking for, we’ve got your covered there too! You might want to also check out his guide on parenthetical citing .

Would you benefit from having a tool that helps you easily generate citations that are in the text? Check out EasyBib Plus!

References page in APA Format

An APA format reference page is easier to create than you probably think. We go into detail on how to create this page on our APA reference page . We also have a guide for how to create an annotated bibliography in APA . But, if you’re simply looking for a brief overview of the reference page, we’ve got you covered here.

Here are some pointers to keep in mind when it comes to the references page in APA format:

• This VIP page has its very own page. Start on a fresh, clean document (p. 303).
• Center and bold the title “References” (do not include quotation marks, underline, or italicize this title).
• Alphabetize and double-space ALL entries.
• Use a readable font, such as Times New Roman, Arial, Calibri, or Lucida (p. 44).
• Every quote or piece of outside information included in the paper should be referenced and have an entry.
• Even though it’s called a “reference page,” it can be longer than one page. If your references flow onto the next page, then that’s a-okay.
• Only include the running head if it is required by your teacher or you’re writing a professional paper.

Sample reference page for a student paper:

Here’s another friendly reminder to use the EasyBib APA format generator (that comes with EasyBib Plus) to quickly and easily develop every single one of your references for you. Try it out! Our APA formatter is easy to use and ready to use 24/7.

Final APA Format Checklist

Prior to submitting your paper, check to make sure you have everything you need and everything in its place:

• Did you credit all of the information and quotes you used in the body of your paper and show a matching full reference at the end of the paper? Remember, you need both! Need more information on how to credit other authors and sources? Check out our other guides, or use the EasyBib APA format generator to credit your sources quickly and easily. EasyBib.com also has more styles than just the one this page focuses on.
• 12-pt. Times New Roman
• 11-pt. Calibri, Arial, Georgia
• 10-pt. Lucida, Sans Unicode, Computer Modern
• If you created an abstract, is it directly after the title page? Some teachers and professors do not require an abstract, so before you go ahead and include it, make sure it’s something he or she is expecting.
• Professional paper — Did you include a running head on every single page of your project?
• Student paper — Did you include page numbers in the upper right-hand corner of all your pages?
• Are all headings, as in section or chapter titles, properly formatted? If you’re not sure, check section number 9.
• Are all tables and figures aligned properly? Did you include notes and other important information directly below the table or figure? Include any information that will help the reader completely understand everything in the table or figure if it were to stand alone.
• Are abbreviations used sparingly? Did you format them properly?
• Is the entire document double spaced?
• Are all numbers formatted properly? Check section 17, which is APA writing format for numbers.
• Did you glance at the sample paper? Is your assignment structured similarly? Are all of the margins uniform?

Submitting Your APA Paper

Congratulations for making it this far! You’ve put a lot of effort into writing your paper and making sure the t’s are crossed and the i’s are dotted. If you’re planning to submit your paper for a school assignment, make sure you review your teacher or professor’s procedures.

If you’re submitting your paper to a journal, you probably need to include a cover letter.

Most cover letters ask you to include:

• The author’s contact information.
• A statement to the editor that the paper is original.
• If a similar paper exists elsewhere, notify the editor in the cover letter.

Once again, review the specific journal’s website for exact specifications for submission.

Okay, so you’re probably thinking you’re ready to hit send or print and submit your assignment. Can we offer one last suggestion? We promise it will only take a minute.

Consider running your paper through our handy dandy paper checker. It’s pretty simple.

Copy and paste or upload your paper into our checker. Within a minute, we’ll provide feedback on your spelling and grammar. If there’s a pronoun , interjection , or verb out of place, we’ll highlight it and offer suggestions for improvement. We’ll even take it a step further and point out any instances of possible plagiarism.

If it sounds too good to be true, then head on over to our innovative tool and give it a whirl. We promise you won’t be disappointed.

What is APA Format?

APA stands for the American Psychological Association . In this guide, you’ll find information related to “What is APA format?” in relation to writing and organizing your paper according to the American Psychological Association’s standards. Information on how to cite sources can be found on our APA citation page. The official American Psychological Association handbook was used as a reference for our guide and we’ve included page numbers from the manual throughout. However, this page is not associated with the association.

You’ll most likely use APA format if your paper is on a scientific topic. Many behavioral and social sciences use this organization’s standards and guidelines.

What are behavioral sciences? Behavioral sciences study human and animal behavior. They can include:

• Cognitive Science
• Neuroscience

What are social sciences? Social sciences focus on one specific aspect of human behavior, specifically social and cultural relationships. Social sciences can include:

• Anthropology
• Political Science
• Human Geography
• Archaeology
• Linguistics

What’s New in the 7th Edition?

This citation style was created by the American Psychological Association. Its rules and guidelines can be found in the Publication Manual of the American Psychological Association . The information provided in the guide above follows the 6th edition (2009) of the manual. The 7th edition was published in 2020 and is the most recent version.

The 7th edition of the Publication Manual is in full color and includes 12 sections (compared to 8 sections in the 6th edition). In general, this new edition differentiates between professional and student papers, includes guidance with accessibility in mind, provides new examples to follow, and has updated guidelines.We’ve selected a few notable updates below, but for a full view of all of the 7th edition changes visit the style’s website linked here .

• Paper title
• Student name
• Affiliation (e.g., school, department, etc.)
• Course number and title
• Course instructor
• 6th edition – Running head: SMARTPHONE EFFECTS ON ADOLESCENT SOCIALIZATION
• 7th edition – SMARTPHONE EFFECTS ON ADOLESCENT SOCIALIZATION
• Pronouns . “They” can be used as a gender-neutral pronoun.
• Bias-free language guidelines . There are updated and new sections on guidelines for this section. New sections address participation in research, socioeconomic status, and intersectionality.
• Spacing after sentences. Add only a single space after end punctuation.
• Tables and figures . The citing format is now streamlined so that both tables and figures should include a name and number above the table/figure, and a note underneath the table/figure.
• 6th ed. – (Ikemoto, Richardson, Murphy, Yoshida 2016)
• 7th ed. – (Ikemoto et al., 2016)
• Citing books. The location of the publisher can be omitted. Also, e-books no longer need to mention the format (e.g., Kindle, etc.)
• Example: https://doi.org/10.1038/s42255-019-0153-5
• Using URLs. URLs no longer need to be prefaced by the words “Retrieved from.”

New citing information . There is new guidance on citing classroom or intranet resources, and oral traditions or traditional knowledge of indigenous peoples.

Visit our EasyBib Twitter feed to discover more citing tips, fun grammar facts, and the latest product updates.

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.) (2020). American Psychological Association. https://doi.org/10.1037/0000165-000

Published October 31, 2011. Updated May 14, 2020.

Written and edited by Michele Kirschenbaum and Elise Barbeau. Michele Kirschenbaum is a school library media specialist and the in-house librarian at EasyBib.com. Elise Barbeau is the Citation Specialist at Chegg. She has worked in digital marketing, libraries, and publishing.

APA Formatting Guide

APA Formatting

• Annotated Bibliography
• Block Quotes
• et al Usage
• Multiple Authors
• Paraphrasing
• Page Numbers
• Parenthetical Citations
• Sample Paper
• View APA Guide

Citation Examples

• Book Chapter
• Journal Article
• Magazine Article
• Newspaper Article
• Website (no author)
• View all APA Examples

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We should not use “et al.” in APA reference list entries. If the number of authors in the source is up to and including 20, list all author names and use an ampersand (&) before the final author’s name. If the number of authors is more than 20, list the first 19 authors’ names followed by an ellipsis (but no ampersand), and then add the final author’s name. An example of author names in a reference entry having more than 20 authors is given below:

Author Surname1, F. M., Author Surname2, F. M., Author Surname3, F. M., Author Surname4, F. M., Author Surname5, F. M., Author Surname6, F. M., Author Surname7, F. M., Author Surname8, F. M., Author Surname9, F. M., Author Surname10, F. M., Author Surname11, F. M., Author Surname12, F. M., Author Surname13, F. M., Author Surname14, F. M., Author Surname15, F. M., Author Surname16, F. M., Author Surname17, F. M., Author Surname18, F. M., Author Surname19, F. M., . . .  Last Author Surname, F. M. (Publication Year).

Alvarez, L. D., Peach, J. L., Rodriguez, J. F., Donald, L., Thomas, M., Aruck, A., Samy, K., Anthony, K., Ajey, M., Rodriguez, K. L., Katherine, K., Vincent, A., Pater, F., Somu, P., Pander, L., Berd, R., Fox, L., Anders, A., Kamala, W., . . . Nicole Jones, K. (2019).

Note that, unlike references with 2 to 20 author names, the symbol “&” is not used here before the last author’s name.

APA 7, released in October 2019, has some new updates. Here is a brief description of the updates made in APA 7.

Different types of papers and best practices are given in detail in Chapter 1.

How to format a student title page is explained in Chapter 2. Examples of a professional paper and a student paper are included.

Chapter 3 provides additional information on qualitative and mixed methods of research.

An update on writing style is included in Chapter 4.

In chapter 5, some best practices for writing with bias-free language are included.

Chapter 6 gives some updates on style elements including using a single space after a period, including a citation with an abbreviation, the treatment of numbers in abstracts, treatment for different types of lists, and the formatting of gene and protein names.

In Chapter 7, additional examples are given for tables and figures for different types of publications.

In Chapter 8, how to format quotations and how to paraphrase text are covered with additional examples. A simplified version of in-text citations is clearly illustrated.

Chapter 9 has many updates: listing all author names up to 20 authors, standardizing DOIs and URLs, and the formatting of an annotated bibliography.

Chapter 10 includes many examples with templates for all reference types. New rules covering the inclusion of the issue number for journals and the omission of publisher location from book references are provided. Explanations of how to cite YouTube videos, power point slides, and TED talks are included.

Chapter 11 includes many legal references for easy understanding.

Chapter 12 provides advice for authors on how to promote their papers.

For more information on some of the changes found in APA 7, check out this EasyBib article .

APA Citation Examples

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APA Citation Guide (7th edition) : Reference List and Sample Paper

• Getting Started
• How do I Cite?
• In-Text Citations
• Reference List and Sample Paper
• Additional Resources

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Quick Rules for an APA Reference List

Your research paper ends with a list of all the sources cited in your paper. Here are some quick rules for this Reference list:

• Begin the reference list on a new page after the text.
• Name it "References," and center the section label in bold at the top of the page.
• Order the reference list alphabetically by author (last name of the first author followed by the initials of the author's given name(s)).
• Alphabetize entries by authors who have the same given name and last name with suffixes indicating birth order chronologically, oldest first.
• Double-space the entire list (both within and between entries).
• Apply a hanging indent of 0.5 in. to each entry. This means that the first line of the reference is flush left and subsequent lines are indented 0.5 in. from the left margin.

Sample Paper with Reference List

The American Psychological Association (APA) has created  a sample paper  that includes explanations of the elements and formatting in APA 7th ed. 

Headings and Title Pages

APA Running Head   This resource discusses how to format running heads in APA style.

APA Title Page: Format and Templates   This article discusses how to format APA title pages and provides templates for MS Word.

• << Previous: In-Text Citations
• Next: Additional Resources >>
• Last Updated: May 16, 2023 3:10 PM
• URL: https://paperpile.libguides.com/apa

APA Citation Style

Citation examples.

• Paper Format
• Style and Grammar Guidelines
• Citation Management Tools
• What's New in the 7th Edition?
• APA Style References Guidelines from the American Psychological Association
• APA Style (OWL - Online Writing Lab, Purdue University)
• Common Reference Examples Handout
• Journal Article
• Magazine Article
• Newspaper Article
• Edited Book Chapter
• Dictionary Entry
• Government Report
• YouTube Video
• Facebook Post
• Webpage on a Website
• Supplemental Reference Examples
• Archival Documents and Collections

Parenthetical citations:  (Grady et al., 2019; Jerrentrup et al., 2018)

Narrative citations:  Grady et al. (2019) and Jerrentrup et al. (2018)

• If a journal article has a DOI, include the DOI in the reference.
• If the journal article does not have a DOI and is from an academic research database, end the reference after the page range (for an explanation of why, see the  database information  page). The reference in this case is the same as for a print journal article.
• Do not include database information in the reference unless the journal article comes from a database that publishes original, proprietary content, such as UpToDate (see an example on the  database information  page).
• If the journal article does not have a DOI but does have a URL that will resolve for readers (e.g., it is from an online journal that is not part of a database), include the URL of the article at the end of the reference.
• If the journal article has an article number instead of a page range, include the article number instead of the page range (as shown in the Jerrentrup et al. example).

Parenthetical citations:  (Rabinowitz, 2019; Sapolsky, 2017)

Narrative citations:  Rabinowitz (2019) and Sapolsky (2017)

• If the book includes a DOI, include the DOI in the reference after the publisher name.
• Do not include the publisher location.
• If the book does not have a DOI and comes from an academic research database, end the book reference after the publisher name. Do not include  database information  in the reference. The reference in this case is the same as for a print book.

Parenthetical citations:  (Schaefer & Shapiro, 2019; Schulman, 2019)

Narrative citations:  Schaefer and Shapiro (2019) and Schulman (2019)

• If a magazine article has a DOI, include the DOI in the reference.
• If the magazine article does not have a DOI and is from an academic research database, end the reference after the page range. Do not include  database information  in the reference. The reference in this case is the same as for a print magazine article.
• If the magazine article does not have a DOI but does have a URL that will resolve for readers (e.g., it is from an online magazine that is not part of a database), include the URL of the article at the end of the reference.
• If the magazine article does not have volume, issue, and/or page numbers (e.g., because it is from an online magazine), omit the missing elements from the reference (as in the Schulman example).

Parenthetical citation:  (Carey, 2019)

Narrative citation:  Carey (2019)

• If the newspaper article is from an academic research database, end the reference after the page range. Do not include  database information  in the reference. The reference in this case is the same as for a print newspaper article.
• If the newspaper article has a URL that will resolve for readers (e.g., it is from an online newspaper), include the URL of the article at the end of the reference.
• If the newspaper article does not have volume, issue, and/or page numbers (e.g., because it is from an online newspaper), omit the missing elements from the reference, as shown in the example.
• If the article is from a news website (e.g., CNN, HuffPost)—one that does not have an associated daily or weekly newspaper—use the format for a  webpage on a website  instead.

Parenthetical citation:  (Aron et al., 2019)

Narrative citation:  Aron et al. (2019)

• If the edited book chapter includes a DOI, include the chapter DOI in the reference after the publisher name.
• If the edited book chapter does not have a DOI and comes from an academic research database, end the edited book chapter reference after the publisher name. Do not include  database information  in the reference. The reference in this case is the same as for a print edited book chapter.
• Do not create references for chapters of authored books. Instead, write a reference for the whole book and cite the chapter in the text if desired (e.g., Kumar, 2017, Chapter 2).

Parenthetical citation:  (Merriam-Webster, n.d.)

Narrative citation:  Merriam-Webster (n.d.)

• Because entries in  Merriam-Webster’s Dictionary  are updated over time and are not archived, include a  retrieval date  in the reference.
• Merriam-Webster is both the author and the publisher, so the name appears in the author element only to avoid repetition.
• To quote a dictionary definition, view the pages on quotations and  how to quote works without page numbers  for guidance. Additionally, here is an example:  Culture  refers to the “customary beliefs, social forms, and material traits of a racial, religious, or social group” (Merriam-Webster, n.d., Definition 1a).

Parenthetical citation:  (National Cancer Institute, 2019)

Narrative citation:  National Cancer Institute (2019)

The specific agency responsible for the report appears as the author. The names of parent agencies not present in the  group author name  appear in the source element as the publisher. This creates concise in-text citations and complete reference list entries.

Parenthetical citation:  (Harvard University, 2019)

Narrative citation:  Harvard University (2019)

• Use the name of the account that uploaded the video as the author.
• If the account did not actually create the work, explain this in the text if it is important for readers to know. However, if that would mean citing a source that appears unauthoritative, you might also look for the author’s YouTube channel, official website, or other social media to see whether the same video is available elsewhere.

Parenthetical citations:  (APA Databases, 2019; Gates, 2019)

Narrative citations:  APA Databases (2019) and Gates (2019)

• Present the name of the individual or group author the same as you would for any other reference. Then provide the Twitter handle (beginning with the @ sign) in square brackets, followed by a period.
• Provide the first 20 words of the tweet as the title. Count a URL, a hashtag, or an emoji as one word each, and include them in the reference if they fall within the first 20 words.
• If the tweet includes an image, a video, a poll, or a thumbnail image with a link, indicate that in brackets after the title: [Image attached], [Video attached], [Thumbnail with link attached].
• The same format used for Twitter is also used for Instagram.  

Parenthetical citation:  (News From Science, 2019)

Narrative citation:  News From Science (2019)

• Provide the first 20 words of the Facebook post as the title. Count a URL or other link, a hashtag, or an emoji as one word each, and include them in the reference if they fall within the first 20 words. 
• If a status update includes images, videos, thumbnail links to outside sources, or content from another Facebook post (such as when sharing a link), indicate that in square brackets.

Parenthetical citations:  (Fagan, 2019; National Institute of Mental Health, 2018; Woodyatt, 2019; World Health Organization, 2018)

Narrative citations:  Fagan (2019), National Institute of Mental Health (2018), Woodyatt (2019), and World Health Organization (2018)

• Provide as specific a  date  as is available on the webpage. This might be a year only; a year and month; or a year, month, and day.
• Italicize the title of a webpage.
• When the author of the webpage and the publisher of the website are the same, omit the publisher name to avoid repetition (as in the World Health Organization example).
• When contents of a page are meant to be updated over time but are not archived, include a  retrieval date  in the reference (as in the Fagan example).
• Use the webpage on a website format for articles from news websites such as CNN and HuffPost (these sites do not have associated daily or weekly newspapers). Use the  newspaper article category  for articles from newspaper websites such as  The New York Times  or  The Washington Post .
• Create a reference to an open educational resources (OER) page only when the materials are available for download directly (i.e., the materials are on the page and/or can be downloaded as PDFs or other files). If you are directed to another website, create a reference to the specific webpage on that website where the materials can be retrieved. Use this format for material in any OER repository, such as OER Commons, OASIS, or MERLOT.
• Do not create a reference or in-text citation for a whole website. To mention a website in general, and not any particular information on that site, provide the name of the website in the text and include the URL in parentheses. For example, you might mention that you used a website to create a survey.

The following supplemental example references are mention in the  Publication Manual:

• retracted journal or magazine article
• edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM)
• edition of the International Statistical Classification of Diseases and Related Health Problems (ICD)
• religious work
• annotated religious work

Archival document and collections are not presented in the  APA Publication Manual, Seventh Edition . This content is available only on the APA Style website .  This guidance has been expanded from the 6th edition.

Archival sources include letters, unpublished manuscripts, limited-circulation brochures and pamphlets, in-house institutional and corporate documents, clippings, and other documents, as well as such nontextual materials as photographs and apparatus, that are in the personal possession of an author, form part of an institutional collection, or are stored in an archive such as the Archives of the History of American Psychology at the University of Akron or the APA Archives. For any documents like these that are available on the open web or via a database (subscription or nonsubscription), follow the reference templates shown in Chapter 10 of the Publication Manual.

The general format for the reference for an archival work includes the author, date, title, and source. The reference examples shown on this page may be modified for collections requiring more or less specific information to locate materials, for different types of collections, or for additional descriptive information (e.g., a translation of a letter). Authors may choose to list correspondence from their own personal collections, but correspondence from other private collections should be listed only with the permission of the collector.

Keep in mind the following principles when creating references to archival documents and collections:

• As with any reference, the purpose is to direct readers to the source, despite the fact that only a single copy of the document may be available and readers may have some difficulty actually seeing a copy.
• Include as much information as is needed to help locate the item with reasonable ease within the repository. For items from collections with detailed finding aids, the name of the collection may be sufficient; for items from collections without finding aids, more information (e.g., call number, box number, file name or number) may be necessary to help locate the item.
• If several letters are cited from the same collection, list the collection as a reference and provide specific identifying information (author, recipient, and date) for each letter in the in-text citations (see Example 3).
• Use square brackets to indicate information that does not appear on the document.
• Use “ca.” (circa) to indicate an estimated date (see Example 5).
• Use italics for titles of archival documents and collections; if the work does not have a title, provide a description in square brackets without italics.
• Separate elements of the source (e.g., the name of a repository, library, university or archive, and the location of the university or archive) with commas. End the source with a period.
• If a publication of limited circulation is available in libraries, the reference may be formatted as usual for published material, without the archival source.
• Note that private letters (vs. those in an archive or repository) are considered personal communications and cited in the text only.

1. Letter from a repository

Frank, L. K. (1935, February 4). [Letter to Robert M. Ogden]. Rockefeller Archive Center (GEB Series 1.3, Box 371, Folder 3877), Tarrytown, NY, United States.

• Parenthetical citation: (Frank, 1935)
• Narrative citation: Frank (1935)
• Because the letter does not have a title, provide a description in square brackets.

2. Letter from a private collection

Zacharius, G. P. (1953, August 15). [Letter to William Rickel (W. Rickel, Trans.)]. Copy in possession of Hendrika Vande Kemp.

• Parenthetical citation: (Zacharius, 1953)
• Narrative citation: Zacharius (1953)
• In this example, Hendrika Vande Kemp is either the author of the paper or the author of the paper has received permission from Hendrika Vande Kemp to cite a letter in Vande Kemp’s private collection in this way. Otherwise, cite a private letter as a  personal communication .

3. Collection of letters from an archive

Allport, G. W. (1930–1967). Correspondence. Gordon W. Allport Papers (HUG 4118.10), Harvard University Archives, Cambridge, MA, United States.

• Parenthetical citation: (Allport, 1930–1967)
• Narrative citation: Allport (1930–1967)

To cite specific letters in the text, provide the author and range of years as shown in the reference list entry, plus details about who wrote the specific letter to whom and when the specific letter was written.

• Parenthetical citation: (Allport, 1930–1967, G. Boring to Allport, December 26, 1937)
• Narrative citation: Allport (1930–1967, Allport to G. Boring, March 1, 1939)
• Use the parenthetical citation format to cite a letter that E. G. Boring wrote to Allport because Allport is the author in the reference. Use either the parenthetical or narrative citation format to cite letters that Allport wrote.

4. Unpublished papers, lectures from an archive or personal collection

Berliner, A. (1959). Notes for a lecture on reminiscences of Wundt and Leipzig. Anna Berliner Memoirs (Box M50), Archives of the History of American Psychology, University of Akron, Akron, OH, United States.

• Parenthetical citation: (Berliner, 1959)
• Narrative citation: Berliner (1959)

5. Archival/historical source for which the author and/or date is known or is reasonably certain but not stated on the document

Allport, A. (presumed). (ca. 1937). Marion Taylor today—by the biographer [Unpublished manuscript]. Marion Taylor Papers, Schlesinger Library, Radcliffe College, Cambridge, MA, United States.

• Parenthetical citation: (Allport, ca. 1937)
• Narrative citation: Allport (ca. 1937)
• Because the author is reasonably certain but not stated on the document, place the word “presumed” in parentheses after the name, followed by a period.
• Because the date is reasonably certain but not stated on the document, the abbreviation “ca.” (which stands for “circa”) appears before the year in parentheses.

6. Archival source with group author

Subcommittee on Mental Hygiene Personnel in School Programs. (1949, November 5–6). Meeting of Subcommittee on Mental Hygiene Personnel in School Programs. David Shakow Papers (M1360), Archives of the History of American Psychology, University of Akron, Akron, OH, United States.

• Parenthetical citation: (Subcommittee on Mental Hygiene Personnel in School Programs, 1949)
• Narrative citation: Subcommittee on Mental Hygiene Personnel in School Programs (1949)

7. Interview recorded and available in an archive

Smith, M. B. (1989, August 12). Interview by C. A. Kiesler [Tape recording]. President’s Oral History Project, American Psychological Association, APA Archives, Washington, DC, United States.

• Parenthetical citation: (Smith, 1989)
• Narrative citation: Smith (1989)
• For interviews and oral histories recorded in an archive, list the interviewee as the author. Include the interviewer’s name in the description.

8. Transcription of a recorded interview, no recording available

Sparkman, C. F. (1973). An oral history with Dr. Colley F. Sparkman/Interviewer: Orley B. Caudill. Mississippi Oral History Program (Vol. 289), University of Southern Mississippi, Hattiesburg, MS, United States.

• Parenthetical citation: (Sparkman, 1973)
• Narrative citation: Sparkman (1973)

9. Newspaper article clipping, historical, in personal collection

Psychoanalysis institute to open. (1948, September 18). [Clipping from an unidentified Dayton, OH, United States, newspaper]. Copy in possession of author.

• Parenthetical citation: (“Psychoanalysis Institute to Open,” 1948)
• Narrative citation: “Psychoanalysis Institute to Open” (1948)
• Use this format only if you are the person who is in possession of the newspaper clipping.

10. Historical publication of limited circulation

Sci-Art Publishers. (1935). Sci-Art publications [Brochure]. Roback Papers (HUGFP 104.50, Box 2, Folder “Miscellaneous Psychological Materials”), Harvard University Archives, Cambridge, MA, United States.

• Parenthetical citation: (Sci-Art Publishers, 1935)
• Narrative citation: Sci-Art Publishers (1935)

11. Archived photographs, no author and no title

[Photographs of Robert M. Yerkes]. (ca. 1917–1954). Robert Mearns Yerkes Papers (Box 137, Folder 2292), Manuscripts and Archives, Yale University Library, New Haven, CT, United States.

• Parenthetical citation: ([Photographs of Robert M. Yerkes], ca. 1917–1954)
• Narrative citation: [Photographs of Robert M. Yerkes] (ca. 1917–1954)
• Because the archived photographs do not have a title, provide a bracketed description instead.
• Because the archived photographs do not have an author, move the bracketed description to the author position of the reference.

12. Microfilm

U.S. Census Bureau. (1880). 1880 U.S. census: Defective, dependent, and delinquent classes schedule: Virginia [Microfilm]. NARA Microfilm Publication T1132 (Rolls 33–34), National Archives and Records Administration, Washington, DC, United States.

• Parenthetical citation: (U.S. Census Bureau, 1880)
• Narrative citation: U.S. Census Bureau (1880)

Read the full APA guidelines on citing ChatGPT 

OpenAI. (2023).  ChatGPT  (Mar 14 version) [Large language model].  https://chat.openai.com/chat

• Parenthetical citation:  (OpenAI, 2023)
• Narrative citation:  OpenAI (2023)

Author:  The author of the model is OpenAI.

Date:  The date is the year of the version you used. Following the template in Section 10.10, you need to include only the year, not the exact date. The version number provides the specific date information a reader might need.

Title:  The name of the model is “ChatGPT,” so that serves as the title and is italicized in your reference, as shown in the template. Although OpenAI labels unique iterations (i.e., ChatGPT-3, ChatGPT-4), they are using “ChatGPT” as the general name of the model, with updates identified with version numbers.

The version number is included after the title in parentheses. The format for the version number in ChatGPT references includes the date because that is how OpenAI is labeling the versions. Different large language models or software might use different version numbering; use the version number in the format the author or publisher provides, which may be a numbering system (e.g., Version 2.0) or other methods.

Bracketed text  is used in references for additional descriptions when they are needed to help a reader understand what’s being cited. References for a number of common sources, such as journal articles and books, do not include bracketed descriptions, but things outside of the typical peer-reviewed system often do. In the case of a reference for ChatGPT, provide the descriptor “Large language model” in square brackets. OpenAI describes ChatGPT-4 as a “large multimodal model,” so that description may be provided instead if you are using ChatGPT-4. Later versions and software or models from other companies may need different descriptions, based on how the publishers describe the model. The goal of the bracketed text is to briefly describe the kind of model to your reader.

Source:  When the publisher name and the author name are the same, do not repeat the publisher name in the source element of the reference, and move directly to the URL. This is the case for ChatGPT. The URL for ChatGPT is  https://chat.openai.com/chat . For other models or products for which you may create a reference, use the URL that links as directly as possible to the source (i.e., the page where you can access the model, not the publisher’s homepage).

What to include and what to exclude

Works included in a reference list.

The reference list provides a reliable way for readers to identify and locate the works cited in a paper. APA Style papers generally include reference lists, not  bibliographies.

In general, each work cited in the text must appear in the reference list, and each work in the reference list must be cited in the text. Check your work carefully before submitting your manuscript or course assignment to ensure no works cited in the text are missing from the reference list and vice versa, with only the following exceptions.

Works Excluded From a Reference List

There are a few kinds of works that are not included in a reference list. Usually a work is not included because readers cannot recover it or because the mention is so broad that readers do not need a reference list entry to understand the use.

Information on works included in a reference list is covered in Sections 2.12 and 8.4 of the  APA Publication Manual, Seventh Edition

*This guidance has been expanded from the 6th edition.*

• Personal communications  such as emails, phone calls, or text messages are cited in the text only, not in the reference list, because readers cannot retrieve personal communications.
• General mentions of whole websites, whole periodicals, and common software and apps in the text do not require in-text citations or reference list entries because the use is broad and the source is familiar.
• The source of an epigraph does not usually appear in the reference list unless the work is a scholarly book or journal. For example, if you open the paper with an inspirational quotation by a famous person, the source of the quotation does not appear in the reference list because the quotation is meant to set the stage for the work, not substantiate a key point.   
• Quotations from research participants in a study you conducted can be presented and discussed in the text but do not need citations or reference list entries. Citations and reference list entries are not necessary because the quotations are part of your original research. They could also compromise participants’ confidentiality, which is an ethical violation.
• References included in a meta-analysis, which are marked with an asterisk in the reference list, may be cited in the text (or not) at the author’s discretion. This exception is relevant only to authors who are conducting a meta-analysis.

DOIs and URLs

The DOI or URL is the final component of a reference list entry. Because so much scholarship is available and/or retrieved online, most reference list entries end with either a DOI or a URL.

• A DOI is a unique alphanumeric string that identifies content and provides a persistent link to its location on the internet. DOIs can be found in database records and the reference lists of published works.
• A URL specifies the location of digital information on the internet and can be found in the address bar of your internet browser. URLs in references should link directly to the cited work when possible.

Follow these guidelines for including DOIs and URLs in references:

• Include a DOI for all works that have a DOI, regardless of whether you used the online version or the print version.
• If a print work does not have a DOI, do not include any DOI or URL in the reference.
• If an online work has both a DOI and a URL, include only the DOI.
• For works without DOIs from websites (not including academic research databases), provide a URL in the reference (as long as the URL will work for readers).
• For works without DOIs from most  academic research databases , do not include a URL or database information in the reference because these works are widely available. The reference should be the same as the reference for a print version of the work.
• For works from databases that publish original, proprietary material available only in that database (such as the UpToDate database) or for works of limited circulation in databases (such as monographs in the ERIC database), include the name of the database or archive and the URL of the work. If the URL requires a login or is session-specific (meaning it will not resolve for readers), provide the URL of the database or archive home page or login page instead of the URL for the work. See the page on including  database information in references  for more information. 
• If the URL is no longer working or no longer provides readers access to the content you intend to cite, follow the guidance for works with  no source .
• Other alphanumeric identifiers such as the International Standard Book Number (ISBN) and the International Standard Serial Number (ISSN) are not included in APA Style references.

Follow these guidelines to format DOIs and URLs:

• Present both DOIs and URLs as hyperlinks (i.e., beginning with “http:” or “https:”).
• Because a hyperlink leads readers directly to the content, it is not necessary to include the words “Retrieved from” or “Accessed from” before a DOI or URL.
• It is acceptable to use either the default display settings for hyperlinks in your word-processing program (e.g., usually blue font, underlined) or plain text that is not underlined.
• Leave links live if the work is to be published or read online.
• Follow the current recommendations of the International DOI Foundation to format DOIs in the reference list, which as of this publication is as follows:

https://doi.org/ xxxxx

• The string “https://doi.org/” is a way of presenting a DOI as a link, and “xxxxx” refers to the DOI number.
• The preferred format of the DOI has changed over time. Although older works use previous formats (e.g., “http:/dx.doi.org/” or “doi:” or “DOI:” before the DOI number), in your reference list, standardize DOIs into the current preferred format for all entries. For example, use  https://doi.org/10.1037/a0040251  in your reference even though that article, published in 2016, presented the number in an older format.
• Copy and paste the DOI or URL from your web browser directly into your reference list to avoid transcription errors. Do not change the capitalization or punctuation of the DOI or URL. Do not add line breaks manually to the hyperlink; it is acceptable if your word-processing program automatically adds a break or moves the hyperlink to its own line.
• Do not add a period after the DOI or URL because this may interfere with link functionality.

When a DOI or URL is long or complex, you may use shortDOIs or shortened URLs if desired.

• Use the  shortDOI service  provided by the International DOI Foundation to create shortDOIs. A work can have only one DOI and only one shortDOI; the shortDOI service will either produce a new shortDOI for a work that has never had one or retrieve an existing shortDOI.
• Some websites provide their own branded shortened URLs, and independent URL shortening services are available as well. Any shortened URL is acceptable in a reference as long as you check the link to ensure that it takes you to the correct location.
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APA Style (7th ed.)

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• Book, eBook, Dissertation
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• In-Text Citation
• Format Your Paper

Format Your Paper

Download and use the editable templates for student papers below: .

• APA 7th ed. Template Document This is an APA format template document in Google Docs. Click on the link -- it will ask for you to make a new copy of the document, which you can save in your own Google Drive with your preferred privacy settings.
• APA 7th ed. Template Document A Microsoft Word document formatted correctly according to APA 7th edition.
• APA 7th ed. Annotated Bibliography template A Microsoft Word document formatted correctly for an annotated bibliography.

Or, view the directions for specific sections below:

Order of Sections (section 2.17)

• Title page including Title, Author, University and Department, Class, Instructor, and Date
• Body (including introduction, literature review or background, discussion, and conclusion)
• Appendices (including tables & figures)

Margins & Page Numbers (sections 2.22-2.24)

• 1 inch at top, bottom, and both sides
• Left aligned paragraphs and leave the right edge ragged (not "right justified")
• Indent first line of each paragraph 1/2 inch from left margin
• Use page numbers, including on the title page, 1/2 inch from top and flush with right margin

Text Format (section 2.19)

• Times New Roman, 12 point
• Calibri, 11 point
• Arial, 11 point
• Lucinda Sans Unicode, 10 point
• Georgia, 11 point
• Double-space and align text to the left
• Use active voice
• Don't overuse technical jargon
• No periods after a web address or DOI in the References list.

Tables and Figures In-Text (chapter 7)

• Label tables and figures numerically (ex. Table 1)
• Give each table column a heading and use separating lines only when necessary
• Design the table and figure so that it can be understood on its own, i.e. it does not require reference to the surrounding text to understand it
• Notes go below tables and figures

Title Page (section 2.3)

• Include the title, your name,  the class name , and  the college's name
• Title should be 12 words or less and summarize the paper's main idea
• No periods or abbreviations
• Do not italicize or underline
• No quotation marks, all capital letters, or bold
• Center horizontally in upper half of the page

Body (section 2.11)

• Align the text to the left with a 1/2-inch left indent on the first line
• Double-space
• As long as there is no Abstract, at the top of the first page, type the title of the paper, centered, in bold , and in Sentence Case Capitalization
• Usually, include sections like these:  introduction, literature review or background,  discussion, and conclusion -- but the specific organization will depend on the paper type
• Spell out long organization names and add the abbreviation in parenthesis, then just use the abbreviation
• Spell out numbers one through nine and use a number for 10 or more
• Use a number for units of measurement, in tables, to represent statistical or math functions, and dates or times

Headings (section 2.26-2.27)

• Level 1: Center, bold , Title Case 
• Level 2: Align left, bold , Title Case
• Level 3: Alight left, bold italics , Title Case
• Level 4: Indented 1/2", bold , Title Case, end with a period. Follow with text. 
• Level 5: Indented 1/2", bold italics , Title Case, end with a period. Follow with text. 

Quotations (sections 8.26-8.33)

• Include short quotations (40 words or less) in-text with quotation marks
• For quotes more than 40 words, indent the entire quote a half inch from the left margin and double-space it with no quotation marks
• When quoting two or more paragraphs from an original source, indent the first line of each paragraph a half inch from the left margin
• Use ellipsis (...) when omitting sections from a quote and use four periods (....) if omitting the end section of a quote

References (section 2.12)

Begins on a new page following the text of your paper and includes complete citations for the resources you've used in your writing.

• References should be centered and bolded at the top of a new page
• Double-space and use hanging indents (where the first line is on the left margin and the following lines are indented a half inch from the left)
• List authors' last name first followed by the first and middle initials (ex. Skinner, B. F.)
• Alphabetize the list by the first author's last name of of each citation (see sections 9.44-9.49)
• Capitalize only the first word, the first after a colon or em dash, and proper nouns
• Don't capitalize the second word of a hyphenated compound
• No quotation marks around titles of articles

Appendices with Tables, Figures, & Illustrations (section 2.14, and chapter 7)

• Include appendices only to help the reader understand, evaluate, or replicate the study or argument
• Put each appendix on a separate page and align left
• For text, do not indent the first paragraph, but do indent the rest
• If you have only one appendix, label it "Appendix"
• If you have two or more appendices, label them "Appendix A", "Appendix B" and so forth as they appear in the body of your paper
• Label tables and figures numerically (ex. Table 1, or Table B1 and Table B2 if Appendix B has two tables) and describe them within the text of the appendix
• Notes go below tables and figures (see samples on p. 210-226)

Annotated Bibliography

Double-space the entire bibliography. give each entry a hanging indent. in the following annotation, indent the entire paragraph a half inch from the left margin and give the first line of each paragraph a half inch indent. see the template document at the top of this page..

• Check with your professor for the length of the annotation and which elements you should evaluate.

These elements are optional, if your professor or field requires them, but they are  not required for student papers: 

Abstract (section 2.9).

• Abstract gets its own page
• Center "Abstract" heading and do not indent the first line of the text
• Summarize the main points and purpose of the paper in 150-250 words maximum
• Define abbreviations and acronyms used in the paper

Running Head (section 2.8 )

• Shorten title to 50 characters or less (counting spaces and punctuation) for the running head
• In the top margin, the running head is aligned left, with the page number aligned on the right
• On every page, put (without the brackets): [SHORTENED TITLE OF YOUR PAPER IN ALL CAPS] [page number] 

More questions? Check out the authoritative source: APA style blog

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Home » References in Research – Types, Examples and Writing Guide

References in Research – Types, Examples and Writing Guide

Table of Contents

References in Research

Definition:

References in research are a list of sources that a researcher has consulted or cited while conducting their study. They are an essential component of any academic work, including research papers, theses, dissertations, and other scholarly publications.

Types of References

There are several types of references used in research, and the type of reference depends on the source of information being cited. The most common types of references include:

References to books typically include the author’s name, title of the book, publisher, publication date, and place of publication.

Example: Smith, J. (2018). The Art of Writing. Penguin Books.

Journal Articles

References to journal articles usually include the author’s name, title of the article, name of the journal, volume and issue number, page numbers, and publication date.

Example: Johnson, T. (2021). The Impact of Social Media on Mental Health. Journal of Psychology, 32(4), 87-94.

Web sources

References to web sources should include the author or organization responsible for the content, the title of the page, the URL, and the date accessed.

Example: World Health Organization. (2020). Coronavirus disease (COVID-19) advice for the public. Retrieved from https://www.who.int/emergencies/disease/novel-coronavirus-2019/advice-for-public

Conference Proceedings

References to conference proceedings should include the author’s name, title of the paper, name of the conference, location of the conference, date of the conference, and page numbers.

Example: Chen, S., & Li, J. (2019). The Future of AI in Education. Proceedings of the International Conference on Educational Technology, Beijing, China, July 15-17, pp. 67-78.

References to reports typically include the author or organization responsible for the report, title of the report, publication date, and publisher.

Example: United Nations. (2020). The Sustainable Development Goals Report. United Nations.

Formats of References

Some common Formates of References with their examples are as follows:

APA (American Psychological Association) Style

The APA (American Psychological Association) Style has specific guidelines for formatting references used in academic papers, articles, and books. Here are the different reference formats in APA style with examples:

Author, A. A. (Year of publication). Title of book. Publisher.

Example : Smith, J. K. (2005). The psychology of social interaction. Wiley-Blackwell.

Journal Article

Author, A. A., Author, B. B., & Author, C. C. (Year of publication). Title of article. Title of Journal, volume number(issue number), page numbers.

Example : Brown, L. M., Keating, J. G., & Jones, S. M. (2012). The role of social support in coping with stress among African American adolescents. Journal of Research on Adolescence, 22(1), 218-233.

Author, A. A. (Year of publication or last update). Title of page. Website name. URL.

Example : Centers for Disease Control and Prevention. (2020, December 11). COVID-19: How to protect yourself and others. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html

Magazine article

Author, A. A. (Year, Month Day of publication). Title of article. Title of Magazine, volume number(issue number), page numbers.

Example : Smith, M. (2019, March 11). The power of positive thinking. Psychology Today, 52(3), 60-65.

Newspaper article:

Author, A. A. (Year, Month Day of publication). Title of article. Title of Newspaper, page numbers.

Example: Johnson, B. (2021, February 15). New study shows benefits of exercise on mental health. The New York Times, A8.

Edited book

Editor, E. E. (Ed.). (Year of publication). Title of book. Publisher.

Example : Thompson, J. P. (Ed.). (2014). Social work in the 21st century. Sage Publications.

Chapter in an edited book:

Author, A. A. (Year of publication). Title of chapter. In E. E. Editor (Ed.), Title of book (pp. page numbers). Publisher.

Example : Johnson, K. S. (2018). The future of social work: Challenges and opportunities. In J. P. Thompson (Ed.), Social work in the 21st century (pp. 105-118). Sage Publications.

MLA (Modern Language Association) Style

The MLA (Modern Language Association) Style is a widely used style for writing academic papers and essays in the humanities. Here are the different reference formats in MLA style:

Author’s Last name, First name. Title of Book. Publisher, Publication year.

Example : Smith, John. The Psychology of Social Interaction. Wiley-Blackwell, 2005.

Journal article

Author’s Last name, First name. “Title of Article.” Title of Journal, volume number, issue number, Publication year, page numbers.

Example : Brown, Laura M., et al. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence, vol. 22, no. 1, 2012, pp. 218-233.

Author’s Last name, First name. “Title of Webpage.” Website Name, Publication date, URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC, 11 Dec. 2020, https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Publication date, page numbers.

Example : Smith, Mary. “The Power of Positive Thinking.” Psychology Today, Mar. 2019, pp. 60-65.

Newspaper article

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Publication date, page numbers.

Example : Johnson, Bob. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, 15 Feb. 2021, p. A8.

Editor’s Last name, First name, editor. Title of Book. Publisher, Publication year.

Example : Thompson, John P., editor. Social Work in the 21st Century. Sage Publications, 2014.

Chapter in an edited book

Author’s Last name, First name. “Title of Chapter.” Title of Book, edited by Editor’s First Name Last name, Publisher, Publication year, page numbers.

Example : Johnson, Karen S. “The Future of Social Work: Challenges and Opportunities.” Social Work in the 21st Century, edited by John P. Thompson, Sage Publications, 2014, pp. 105-118.

Chicago Manual of Style

The Chicago Manual of Style is a widely used style for writing academic papers, dissertations, and books in the humanities and social sciences. Here are the different reference formats in Chicago style:

Example : Smith, John K. The Psychology of Social Interaction. Wiley-Blackwell, 2005.

Author’s Last name, First name. “Title of Article.” Title of Journal volume number, no. issue number (Publication year): page numbers.

Example : Brown, Laura M., John G. Keating, and Sarah M. Jones. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence 22, no. 1 (2012): 218-233.

Author’s Last name, First name. “Title of Webpage.” Website Name. Publication date. URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC. December 11, 2020. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Publication date.

Example : Smith, Mary. “The Power of Positive Thinking.” Psychology Today, March 2019.

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Publication date.

Example : Johnson, Bob. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Example : Thompson, John P., ed. Social Work in the 21st Century. Sage Publications, 2014.

Author’s Last name, First name. “Title of Chapter.” In Title of Book, edited by Editor’s First Name Last Name, page numbers. Publisher, Publication year.

Example : Johnson, Karen S. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by John P. Thompson, 105-118. Sage Publications, 2014.

Harvard Style

The Harvard Style, also known as the Author-Date System, is a widely used style for writing academic papers and essays in the social sciences. Here are the different reference formats in Harvard Style:

Author’s Last name, First name. Year of publication. Title of Book. Place of publication: Publisher.

Example : Smith, John. 2005. The Psychology of Social Interaction. Oxford: Wiley-Blackwell.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Journal volume number (issue number): page numbers.

Example: Brown, Laura M., John G. Keating, and Sarah M. Jones. 2012. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence 22 (1): 218-233.

Author’s Last name, First name. Year of publication. “Title of Webpage.” Website Name. URL. Accessed date.

Example : Centers for Disease Control and Prevention. 2020. “COVID-19: How to Protect Yourself and Others.” CDC. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html. Accessed April 1, 2023.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Magazine, month and date of publication.

Example : Smith, Mary. 2019. “The Power of Positive Thinking.” Psychology Today, March 2019.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Newspaper, month and date of publication.

Example : Johnson, Bob. 2021. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Editor’s Last name, First name, ed. Year of publication. Title of Book. Place of publication: Publisher.

Example : Thompson, John P., ed. 2014. Social Work in the 21st Century. Thousand Oaks, CA: Sage Publications.

Author’s Last name, First name. Year of publication. “Title of Chapter.” In Title of Book, edited by Editor’s First Name Last Name, page numbers. Place of publication: Publisher.

Example : Johnson, Karen S. 2014. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by John P. Thompson, 105-118. Thousand Oaks, CA: Sage Publications.

Vancouver Style

The Vancouver Style, also known as the Uniform Requirements for Manuscripts Submitted to Biomedical Journals, is a widely used style for writing academic papers in the biomedical sciences. Here are the different reference formats in Vancouver Style:

Author’s Last name, First name. Title of Book. Edition number. Place of publication: Publisher; Year of publication.

Example : Smith, John K. The Psychology of Social Interaction. 2nd ed. Oxford: Wiley-Blackwell; 2005.

Author’s Last name, First name. Title of Article. Abbreviated Journal Title. Year of publication; volume number(issue number):page numbers.

Example : Brown LM, Keating JG, Jones SM. The Role of Social Support in Coping with Stress among African American Adolescents. J Res Adolesc. 2012;22(1):218-233.

Author’s Last name, First name. Title of Webpage. Website Name [Internet]. Publication date. [cited date]. Available from: URL.

Example : Centers for Disease Control and Prevention. COVID-19: How to Protect Yourself and Others [Internet]. 2020 Dec 11. [cited 2023 Apr 1]. Available from: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. Title of Article. Title of Magazine. Year of publication; month and day of publication:page numbers.

Example : Smith M. The Power of Positive Thinking. Psychology Today. 2019 Mar 1:32-35.

Author’s Last name, First name. Title of Article. Title of Newspaper. Year of publication; month and day of publication:page numbers.

Example : Johnson B. New Study Shows Benefits of Exercise on Mental Health. The New York Times. 2021 Feb 15:A4.

Editor’s Last name, First name, editor. Title of Book. Edition number. Place of publication: Publisher; Year of publication.

Example: Thompson JP, editor. Social Work in the 21st Century. 1st ed. Thousand Oaks, CA: Sage Publications; 2014.

Author’s Last name, First name. Title of Chapter. In: Editor’s Last name, First name, editor. Title of Book. Edition number. Place of publication: Publisher; Year of publication. page numbers.

Example : Johnson KS. The Future of Social Work: Challenges and Opportunities. In: Thompson JP, editor. Social Work in the 21st Century. 1st ed. Thousand Oaks, CA: Sage Publications; 2014. p. 105-118.

Turabian Style

Turabian style is a variation of the Chicago style used in academic writing, particularly in the fields of history and humanities. Here are the different reference formats in Turabian style:

Author’s Last name, First name. Title of Book. Place of publication: Publisher, Year of publication.

Example : Smith, John K. The Psychology of Social Interaction. Oxford: Wiley-Blackwell, 2005.

Author’s Last name, First name. “Title of Article.” Title of Journal volume number, no. issue number (Year of publication): page numbers.

Example : Brown, LM, Keating, JG, Jones, SM. “The Role of Social Support in Coping with Stress among African American Adolescents.” J Res Adolesc 22, no. 1 (2012): 218-233.

Author’s Last name, First name. “Title of Webpage.” Name of Website. Publication date. Accessed date. URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC. December 11, 2020. Accessed April 1, 2023. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Month Day, Year of publication, page numbers.

Example : Smith, M. “The Power of Positive Thinking.” Psychology Today, March 1, 2019, 32-35.

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Month Day, Year of publication.

Example : Johnson, B. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Editor’s Last name, First name, ed. Title of Book. Place of publication: Publisher, Year of publication.

Example : Thompson, JP, ed. Social Work in the 21st Century. Thousand Oaks, CA: Sage Publications, 2014.

Author’s Last name, First name. “Title of Chapter.” In Title of Book, edited by Editor’s Last name, First name, page numbers. Place of publication: Publisher, Year of publication.

Example : Johnson, KS. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by Thompson, JP, 105-118. Thousand Oaks, CA: Sage Publications, 2014.

IEEE (Institute of Electrical and Electronics Engineers) Style

IEEE (Institute of Electrical and Electronics Engineers) style is commonly used in engineering, computer science, and other technical fields. Here are the different reference formats in IEEE style:

Author’s Last name, First name. Book Title. Place of Publication: Publisher, Year of publication.

Example : Oppenheim, A. V., & Schafer, R. W. Discrete-Time Signal Processing. Upper Saddle River, NJ: Prentice Hall, 2010.

Author’s Last name, First name. “Title of Article.” Abbreviated Journal Title, vol. number, no. issue number, pp. page numbers, Month year of publication.

Example: Shannon, C. E. “A Mathematical Theory of Communication.” Bell System Technical Journal, vol. 27, no. 3, pp. 379-423, July 1948.

Conference paper

Author’s Last name, First name. “Title of Paper.” In Title of Conference Proceedings, Place of Conference, Date of Conference, pp. page numbers, Year of publication.

Example: Gupta, S., & Kumar, P. “An Improved System of Linear Discriminant Analysis for Face Recognition.” In Proceedings of the 2011 International Conference on Computer Science and Network Technology, Harbin, China, Dec. 2011, pp. 144-147.

Author’s Last name, First name. “Title of Webpage.” Name of Website. Date of publication or last update. Accessed date. URL.

Example : National Aeronautics and Space Administration. “Apollo 11.” NASA. July 20, 1969. Accessed April 1, 2023. https://www.nasa.gov/mission_pages/apollo/apollo11.html.

Technical report

Author’s Last name, First name. “Title of Report.” Name of Institution or Organization, Report number, Year of publication.

Example : Smith, J. R. “Development of a New Solar Panel Technology.” National Renewable Energy Laboratory, NREL/TP-6A20-51645, 2011.

Author’s Last name, First name. “Title of Patent.” Patent number, Issue date.

Example : Suzuki, H. “Method of Producing Carbon Nanotubes.” US Patent 7,151,019, December 19, 2006.

Standard Title. Standard number, Publication date.

Example : IEEE Standard for Floating-Point Arithmetic. IEEE Std 754-2008, August 29, 2008

ACS (American Chemical Society) Style

ACS (American Chemical Society) style is commonly used in chemistry and related fields. Here are the different reference formats in ACS style:

Author’s Last name, First name; Author’s Last name, First name. Title of Article. Abbreviated Journal Title Year, Volume, Page Numbers.

Example : Wang, Y.; Zhao, X.; Cui, Y.; Ma, Y. Facile Preparation of Fe3O4/graphene Composites Using a Hydrothermal Method for High-Performance Lithium Ion Batteries. ACS Appl. Mater. Interfaces 2012, 4, 2715-2721.

Author’s Last name, First name. Book Title; Publisher: Place of Publication, Year of Publication.

Example : Carey, F. A. Organic Chemistry; McGraw-Hill: New York, 2008.

Author’s Last name, First name. Chapter Title. In Book Title; Editor’s Last name, First name, Ed.; Publisher: Place of Publication, Year of Publication; Volume number, Chapter number, Page Numbers.

Example : Grossman, R. B. Analytical Chemistry of Aerosols. In Aerosol Measurement: Principles, Techniques, and Applications; Baron, P. A.; Willeke, K., Eds.; Wiley-Interscience: New York, 2001; Chapter 10, pp 395-424.

Author’s Last name, First name. Title of Webpage. Website Name, URL (accessed date).

Example : National Institute of Standards and Technology. Atomic Spectra Database. https://www.nist.gov/pml/atomic-spectra-database (accessed April 1, 2023).

Author’s Last name, First name. Patent Number. Patent Date.

Example : Liu, Y.; Huang, H.; Chen, H.; Zhang, W. US Patent 9,999,999, December 31, 2022.

Author’s Last name, First name; Author’s Last name, First name. Title of Article. In Title of Conference Proceedings, Publisher: Place of Publication, Year of Publication; Volume Number, Page Numbers.

Example : Jia, H.; Xu, S.; Wu, Y.; Wu, Z.; Tang, Y.; Huang, X. Fast Adsorption of Organic Pollutants by Graphene Oxide. In Proceedings of the 15th International Conference on Environmental Science and Technology, American Chemical Society: Washington, DC, 2017; Volume 1, pp 223-228.

AMA (American Medical Association) Style

AMA (American Medical Association) style is commonly used in medical and scientific fields. Here are the different reference formats in AMA style:

Author’s Last name, First name. Article Title. Journal Abbreviation. Year; Volume(Issue):Page Numbers.

Example : Jones, R. A.; Smith, B. C. The Role of Vitamin D in Maintaining Bone Health. JAMA. 2019;321(17):1765-1773.

Author’s Last name, First name. Book Title. Edition number. Place of Publication: Publisher; Year.

Example : Guyton, A. C.; Hall, J. E. Textbook of Medical Physiology. 13th ed. Philadelphia, PA: Saunders; 2015.

Author’s Last name, First name. Chapter Title. In: Editor’s Last name, First name, ed. Book Title. Edition number. Place of Publication: Publisher; Year: Page Numbers.

Example: Rajakumar, K. Vitamin D and Bone Health. In: Holick, M. F., ed. Vitamin D: Physiology, Molecular Biology, and Clinical Applications. 2nd ed. New York, NY: Springer; 2010:211-222.

Author’s Last name, First name. Webpage Title. Website Name. URL. Published date. Updated date. Accessed date.

Example : National Cancer Institute. Breast Cancer Prevention (PDQ®)–Patient Version. National Cancer Institute. https://www.cancer.gov/types/breast/patient/breast-prevention-pdq. Published October 11, 2022. Accessed April 1, 2023.

Author’s Last name, First name. Conference presentation title. In: Conference Title; Conference Date; Place of Conference.

Example : Smith, J. R. Vitamin D and Bone Health: A Meta-Analysis. In: Proceedings of the Annual Meeting of the American Society for Bone and Mineral Research; September 20-23, 2022; San Diego, CA.

Thesis or dissertation

Author’s Last name, First name. Title of Thesis or Dissertation. Degree level [Doctoral dissertation or Master’s thesis]. University Name; Year.

Example : Wilson, S. A. The Effects of Vitamin D Supplementation on Bone Health in Postmenopausal Women [Doctoral dissertation]. University of California, Los Angeles; 2018.

ASCE (American Society of Civil Engineers) Style

The ASCE (American Society of Civil Engineers) style is commonly used in civil engineering fields. Here are the different reference formats in ASCE style:

Author’s Last name, First name. “Article Title.” Journal Title, volume number, issue number (year): page numbers. DOI or URL (if available).

Example : Smith, J. R. “Evaluation of the Effectiveness of Sustainable Drainage Systems in Urban Areas.” Journal of Environmental Engineering, vol. 146, no. 3 (2020): 04020010. https://doi.org/10.1061/(ASCE)EE.1943-7870.0001668.

Example : McCuen, R. H. Hydrologic Analysis and Design. 4th ed. Upper Saddle River, NJ: Pearson Education; 2013.

Author’s Last name, First name. “Chapter Title.” In: Editor’s Last name, First name, ed. Book Title. Edition number. Place of Publication: Publisher; Year: page numbers.

Example : Maidment, D. R. “Floodplain Management in the United States.” In: Shroder, J. F., ed. Treatise on Geomorphology. San Diego, CA: Academic Press; 2013: 447-460.

Author’s Last name, First name. “Paper Title.” In: Conference Title; Conference Date; Location. Place of Publication: Publisher; Year: page numbers.

Example: Smith, J. R. “Sustainable Drainage Systems for Urban Areas.” In: Proceedings of the ASCE International Conference on Sustainable Infrastructure; November 6-9, 2019; Los Angeles, CA. Reston, VA: American Society of Civil Engineers; 2019: 156-163.

Author’s Last name, First name. “Report Title.” Report number. Place of Publication: Publisher; Year.

Example : U.S. Army Corps of Engineers. “Hurricane Sandy Coastal Risk Reduction Program, New York and New Jersey.” Report No. P-15-001. Washington, DC: U.S. Army Corps of Engineers; 2015.

CSE (Council of Science Editors) Style

The CSE (Council of Science Editors) style is commonly used in the scientific and medical fields. Here are the different reference formats in CSE style:

Author’s Last name, First Initial. Middle Initial. “Article Title.” Journal Title. Year;Volume(Issue):Page numbers.

Example : Smith, J.R. “Evaluation of the Effectiveness of Sustainable Drainage Systems in Urban Areas.” Journal of Environmental Engineering. 2020;146(3):04020010.

Author’s Last name, First Initial. Middle Initial. Book Title. Edition number. Place of Publication: Publisher; Year.

Author’s Last name, First Initial. Middle Initial. “Chapter Title.” In: Editor’s Last name, First Initial. Middle Initial., ed. Book Title. Edition number. Place of Publication: Publisher; Year:Page numbers.

Author’s Last name, First Initial. Middle Initial. “Paper Title.” In: Conference Title; Conference Date; Location. Place of Publication: Publisher; Year.

Example : Smith, J.R. “Sustainable Drainage Systems for Urban Areas.” In: Proceedings of the ASCE International Conference on Sustainable Infrastructure; November 6-9, 2019; Los Angeles, CA. Reston, VA: American Society of Civil Engineers; 2019.

Author’s Last name, First Initial. Middle Initial. “Report Title.” Report number. Place of Publication: Publisher; Year.

Bluebook Style

The Bluebook style is commonly used in the legal field for citing legal documents and sources. Here are the different reference formats in Bluebook style:

Case citation

Case name, volume source page (Court year).

Example : Brown v. Board of Education, 347 U.S. 483 (1954).

Statute citation

Name of Act, volume source § section number (year).

Example : Clean Air Act, 42 U.S.C. § 7401 (1963).

Regulation citation

Name of regulation, volume source § section number (year).

Example: Clean Air Act, 40 C.F.R. § 52.01 (2019).

Book citation

Author’s Last name, First Initial. Middle Initial. Book Title. Edition number (if applicable). Place of Publication: Publisher; Year.

Example: Smith, J.R. Legal Writing and Analysis. 3rd ed. New York, NY: Aspen Publishers; 2015.

Journal article citation

Author’s Last name, First Initial. Middle Initial. “Article Title.” Journal Title. Volume number (year): first page-last page.

Example: Garcia, C. “The Right to Counsel: An International Comparison.” International Journal of Legal Information. 43 (2015): 63-94.

Website citation

Author’s Last name, First Initial. Middle Initial. “Page Title.” Website Title. URL (accessed month day, year).

Example : United Nations. “Universal Declaration of Human Rights.” United Nations. https://www.un.org/en/universal-declaration-human-rights/ (accessed January 3, 2023).

Oxford Style

The Oxford style, also known as the Oxford referencing system or the documentary-note citation system, is commonly used in the humanities, including literature, history, and philosophy. Here are the different reference formats in Oxford style:

Author’s Last name, First name. Book Title. Place of Publication: Publisher, Year of Publication.

Example : Smith, John. The Art of Writing. New York: Penguin, 2020.

Author’s Last name, First name. “Article Title.” Journal Title volume, no. issue (year): page range.

Example: Garcia, Carlos. “The Role of Ethics in Philosophy.” Philosophy Today 67, no. 3 (2019): 53-68.

Chapter in an edited book citation

Author’s Last name, First name. “Chapter Title.” In Book Title, edited by Editor’s Name, page range. Place of Publication: Publisher, Year of Publication.

Example : Lee, Mary. “Feminism in the 21st Century.” In The Oxford Handbook of Feminism, edited by Jane Smith, 51-69. Oxford: Oxford University Press, 2018.

Author’s Last name, First name. “Page Title.” Website Title. URL (accessed day month year).

Example : Jones, David. “The Importance of Learning Languages.” Oxford Language Center. https://www.oxfordlanguagecenter.com/importance-of-learning-languages/ (accessed 3 January 2023).

Dissertation or thesis citation

Author’s Last name, First name. “Title of Dissertation/Thesis.” PhD diss., University Name, Year of Publication.

Example : Brown, Susan. “The Art of Storytelling in American Literature.” PhD diss., University of Oxford, 2020.

Newspaper article citation

Author’s Last name, First name. “Article Title.” Newspaper Title, Month Day, Year.

Example : Robinson, Andrew. “New Developments in Climate Change Research.” The Guardian, September 15, 2022.

AAA (American Anthropological Association) Style

The American Anthropological Association (AAA) style is commonly used in anthropology research papers and journals. Here are the different reference formats in AAA style:

Author’s Last name, First name. Year of Publication. Book Title. Place of Publication: Publisher.

Example : Smith, John. 2019. The Anthropology of Food. New York: Routledge.

Author’s Last name, First name. Year of Publication. “Article Title.” Journal Title volume, no. issue: page range.

Example : Garcia, Carlos. 2021. “The Role of Ethics in Anthropology.” American Anthropologist 123, no. 2: 237-251.

Author’s Last name, First name. Year of Publication. “Chapter Title.” In Book Title, edited by Editor’s Name, page range. Place of Publication: Publisher.

Example: Lee, Mary. 2018. “Feminism in Anthropology.” In The Oxford Handbook of Feminism, edited by Jane Smith, 51-69. Oxford: Oxford University Press.

Author’s Last name, First name. Year of Publication. “Page Title.” Website Title. URL (accessed day month year).

Example : Jones, David. 2020. “The Importance of Learning Languages.” Oxford Language Center. https://www.oxfordlanguagecenter.com/importance-of-learning-languages/ (accessed January 3, 2023).

Author’s Last name, First name. Year of Publication. “Title of Dissertation/Thesis.” PhD diss., University Name.

Example : Brown, Susan. 2022. “The Art of Storytelling in Anthropology.” PhD diss., University of California, Berkeley.

Author’s Last name, First name. Year of Publication. “Article Title.” Newspaper Title, Month Day.

Example : Robinson, Andrew. 2021. “New Developments in Anthropology Research.” The Guardian, September 15.

AIP (American Institute of Physics) Style

The American Institute of Physics (AIP) style is commonly used in physics research papers and journals. Here are the different reference formats in AIP style:

Example : Johnson, S. D. 2021. “Quantum Computing and Information.” Journal of Applied Physics 129, no. 4: 043102.

Example : Feynman, Richard. 2018. The Feynman Lectures on Physics. New York: Basic Books.

Example : Jones, David. 2020. “The Future of Quantum Computing.” In The Handbook of Physics, edited by John Smith, 125-136. Oxford: Oxford University Press.

Conference proceedings citation

Author’s Last name, First name. Year of Publication. “Title of Paper.” Proceedings of Conference Name, date and location: page range. Place of Publication: Publisher.

Example : Chen, Wei. 2019. “The Applications of Nanotechnology in Solar Cells.” Proceedings of the 8th International Conference on Nanotechnology, July 15-17, Tokyo, Japan: 224-229. New York: AIP Publishing.

Example : American Institute of Physics. 2022. “About AIP Publishing.” AIP Publishing. https://publishing.aip.org/about-aip-publishing/ (accessed January 3, 2023).

Patent citation

Author’s Last name, First name. Year of Publication. Patent Number.

Example : Smith, John. 2018. US Patent 9,873,644.

References Writing Guide

Here are some general guidelines for writing references:

• Follow the citation style guidelines: Different disciplines and journals may require different citation styles (e.g., APA, MLA, Chicago). It is important to follow the specific guidelines for the citation style required.
• Include all necessary information : Each citation should include enough information for readers to locate the source. For example, a journal article citation should include the author(s), title of the article, journal title, volume number, issue number, page numbers, and publication year.
• Use proper formatting: Citation styles typically have specific formatting requirements for different types of sources. Make sure to follow the proper formatting for each citation.
• Order citations alphabetically: If listing multiple sources, they should be listed alphabetically by the author’s last name.
• Be consistent: Use the same citation style throughout the entire paper or project.
• Check for accuracy: Double-check all citations to ensure accuracy, including correct spelling of author names and publication information.
• Use reputable sources: When selecting sources to cite, choose reputable and authoritative sources. Avoid sources that are biased or unreliable.
• Include all sources: Make sure to include all sources used in the research, including those that were not directly quoted but still informed the work.
• Use online tools : There are online tools available (e.g., citation generators) that can help with formatting and organizing references.

Purpose of References in Research

References in research serve several purposes:

• To give credit to the original authors or sources of information used in the research. It is important to acknowledge the work of others and avoid plagiarism.
• To provide evidence for the claims made in the research. References can support the arguments, hypotheses, or conclusions presented in the research by citing relevant studies, data, or theories.
• To allow readers to find and verify the sources used in the research. References provide the necessary information for readers to locate and access the sources cited in the research, which allows them to evaluate the quality and reliability of the information presented.
• To situate the research within the broader context of the field. References can show how the research builds on or contributes to the existing body of knowledge, and can help readers to identify gaps in the literature that the research seeks to address.

Importance of References in Research

References play an important role in research for several reasons:

• Credibility : By citing authoritative sources, references lend credibility to the research and its claims. They provide evidence that the research is based on a sound foundation of knowledge and has been carefully researched.
• Avoidance of Plagiarism : References help researchers avoid plagiarism by giving credit to the original authors or sources of information. This is important for ethical reasons and also to avoid legal repercussions.
• Reproducibility : References allow others to reproduce the research by providing detailed information on the sources used. This is important for verification of the research and for others to build on the work.
• Context : References provide context for the research by situating it within the broader body of knowledge in the field. They help researchers to understand where their work fits in and how it builds on or contributes to existing knowledge.
• Evaluation : References provide a means for others to evaluate the research by allowing them to assess the quality and reliability of the sources used.

Advantages of References in Research

There are several advantages of including references in research:

• Acknowledgment of Sources: Including references gives credit to the authors or sources of information used in the research. This is important to acknowledge the original work and avoid plagiarism.
• Evidence and Support : References can provide evidence to support the arguments, hypotheses, or conclusions presented in the research. This can add credibility and strength to the research.
• Reproducibility : References provide the necessary information for others to reproduce the research. This is important for the verification of the research and for others to build on the work.
• Context : References can help to situate the research within the broader body of knowledge in the field. This helps researchers to understand where their work fits in and how it builds on or contributes to existing knowledge.
• Evaluation : Including references allows others to evaluate the research by providing a means to assess the quality and reliability of the sources used.
• Ongoing Conversation: References allow researchers to engage in ongoing conversations and debates within their fields. They can show how the research builds on or contributes to the existing body of knowledge.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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Citing Sources: Sample Reference List Citations

• Style Links & Samples
• Sample Reference List Citations
• Sample Notes and Bibliography Citations
• Sample Author Date Citations
• Citing Nontraditional Sources in Chicago
• Sample Citations
• Major Changes to the New MLA
• Capitalization and Personal Names in Foreign Languages
• Citing Primary Sources
• Ancient Texts
• Citation Consultations Policy

When formatting a citation in APA style, pay particular attention to italics, punctuation, indentation, and capitalization.

Many more samples of citations presented in the APA style can be found in the Publication Manual of the American Psychological Association . Please consult this book or a librarian for help with unusual resources.

All of the following samples are taken from:

American Psychological Association. (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: American Psychological Association.

(In the above sample, the name of the organization is the author. Note that only proper names are capitalized in the title, and the edition number follows the title.)

Book: (This sample from Purdue OWL )

Calfee, R. C., & Valencia, R. R. (1991).  APA guide to preparing manuscripts for journal publication . Washington, DC: American Psychological Association.

Book with an Editor:

Robinson, D. N. (Ed.). (1992). Social discourse and moral judgment . San Diego, CA: Academic Press.

Note: italicize the title of the book and do not capitalize any words in titles except the first word, proper names, and after a colon. Use the author's or editor's initials only for first and middle names.

Chapter from an Edited Volume or Anthology :

Haybron, D. M. (2008). Philosophy and the science of subjective well-being. In M. Eid & R. J. Larsen (Eds.),  The science of subjective well-being  (pp. 17-43). New York, NY: Guilford Press. 

Scholarly Article:

Fuentes, A. (2016). Contemporary evolutionary theory in biological anthropology: Insight into human evolution,  genomics  and challenges to  racialized  pseudo-science.   Revista   Cuicuilco , 23 (65), 293-304. 

Note: Do not set off the title of the article with quotes, italics, underlines, or capital letters (except for the first word, proper names or after a colon). Italicize the title of the journal and capitalize all words in the title of the journal. This sample includes the volume number (23) which is italicized to set it off from the other numbers. The issue number (65) appears in parentheses and is not italicized. You will also notice that there is no space left between the volume number and the first parenthesis for the issue number.

Scholarly Article (with multiple authors):

Calvo, M. G., & Lang, P. J. (2004). Gaze patterns when looking at emotional pictures: Motivationally biased attention. Motivation and Emotion, 28 , 221-243. https://doi.org/10.1023/B:MOEM.0000040153.26156.ed

Note: This sample includes the volume number (28), which is italicized to set it off from the page numbers. There is no issue number in this example because the journal is paginated by volume. Provide the DOI when available for electronic documents. If a DOI is not available for a scholarly article retrieved online, you should supply the URL of the journal's homepage (NOT the URL from the database). Note authors' names, indentations, spare use of capital letters, page numbers, and use of periods and commas.

Popular Article (with two authors):

Kandel, E. R., & Squire, L. R. (2000, November 10). Neuroscience: Breaking down scientific barriers to the study of brain and mind. Science, 290, 1113-1120.

Note: Do not set off the title of the article with quotes, italics, underlines, or capital letters (except for the first word, proper names, or after a colon). Italicize the title of the magazine and capitalize all keywords in the title. Italicize the volume number to set it off from the page numbers.

Newspaper Article:

Scwartz, J. (1993, September 30). Obesity affects economic, social status. The Washington Post , pp. A1, A4.

Note: Do not set off the title of the article with quotes, italics, underlines, or capital letters (except for the first word, proper names or after a colon). Italicize the title of the newspaper and capitalize all keywords in the title of the newspaper.

Webpage Examples:  (These samples from  Purdue OWL )

Author, A. A. & Author B. B. (Date of publication ,  or  n. d. if no date ). Title of page [Format description when necessary]. Retrieved from https://www.someaddress.com/full/url/

Eco, U. (2015). How to write a thesis [PDF file]. (Farina C. M. & Farina F., Trans.) Retrieved from https://www.researchgate.net/...How_to_write_a_thesis/.../Umberto+Eco-How+to+Write+... (Original work published 1977).

If the page's author is not listed, start with the title. If the date of publication is not listed, use the abbreviation (n.d.):

Spotlight Resources. (n.d.). Retrieved from https://owl.purdue.edu/owl/about_the_owl/owl_information/spotlight_resources.html

Only include a date of access when page content is likely to change over time (ex: if you're citing a wiki):

Purdue University Writing Lab [Facebook page]. (n.d.). Retrieved January 22, 2019, from https://www.facebook.com/PurdueUniversityWritingLab/

Nonperiodical Web Document or Report (Examples: government data such as U.S. Census): (This sample from Purdue OWL )

Author, A. A., & Author, B. B. (Date of publication, or n.d. if no date).  Title of document . Retrieved from https://Web address

Angeli, E., Wagner, J., Lawrick, E., Moore, K., Anderson, M., Soderland, L., & Brizee, A. (2010, May 5).  General format.  Retrieved from http://owl.english.purdue.edu/owl/resource/560/01/

Note: Italicize the title of the website but do not capitalize any words except the first, proper names, and the first word following a colon.

For citing company or industry reports from the library's MarketLine database, also see:

https://guides.library.ualberta.ca/apa-citation-style/business

Publication manual of the American Psychological Association 7.07

If map is within a book, cite as In Title of book after [Type of map].

Cite primary contributors in the Author's space followed by their contributing role in parentheses.

Other forms for [Type of map] include:

• [Demographic map]
• [Topographical map]

Use (n.d.) for No date.

Title of map. (Year). [Type of Map]. Publisher Location: Publisher.

Citation Examples:

Plattsburgh, Clinton County: Dannemora, Peru, Keeseville, Champlain, Rouses Point, New York State, 3rd ed.

(1999). [Road map]. Clifton Park, NY: Jimapco.

Topographical Map:

Berlin, N.Y. - Mass. - VT. (1988). [Topographical map]. reston, VA: U.S. Geological Survey.

Online Map:

Follow the map citation guidelines as above, but also include a stable URL where the map is found.

Title of map. (Year). [Type of map]. Retrieved from http://xxx.xx

Manhattan sightseeing map. (2010). [City map]. Retrieved from http://www.ny.com/maps/shopmap.html

MTA Metro-North railroad. (2010). [Railroad map]. Retrieved from http://www.mta.info/mnr/html/mnrmap.htm

MTA New York City subway. (2010). [Subway map]. Retrieved from http://www.mta.info/nyct/maps/submap.htm

Charts and Graphs

Since the APA manual does not give direct information for citing every type of source, including charts or graphs, they instruct you to follow the example that is most like the source you are trying to cite. Be sure to provide enough information so your readers can locate the source on their own. When possible provide author or creator, year of publication, title, and publishing and/or retrieval data. When citing a chart, graph or map it may be best to follow the citation style for the format in which the information is presented.

All captions for charts should follow the guidelines below for captions for figures.

Captions for Figures (Charts, Graphs, and Maps): Publication manual of the American Psychological Association 5.20-5.25

All captions should be labeled as Figure followed by a number. The caption should begin with a descriptive phrase and include a citation to the original source and copyright information at the end.

Figure 1. Relations between trust beliefs and school adjustment at T1 and loneliness changes during development in early childhood. All paths attained significance at p> .05. Adapted from “The Relation Between Trust Beliefs and Loneliness During Early Childhood, Middle Childhood, and Adulthood,” by K. J. Rotenberg, N. Addis, L. R. Betts, A. Corrigan, C. Fox, Z. Hobson, & … and M. J. Boulton, 2010, Personality and social psychology bulletin , 36, p. 1090. Copyright 2010 by the Society for Personality and Social Psychology, Inc.

Documentaries or Feature Films:

David, L., Bender, L., Burns S.Z. (Producers), & Guggenheim, P.D. (Director). (2006). An inconvenient truth [Motion picture]. United States: Paramount Pictures.

Note : If a film is not available in wide distribution, add the following to the citation after the country of origin: (Available from Distributor name, full address and zip code).

Online Resources

More examples and samples of papers written using the APA style can be found at the following websites:

• APA Style.Org The APA Citation Style's official website, as excerpted from the 6th edition.
• Excelsior College OWL APA style guide from Excelsior College's Online Writing Lab.
• Slate Citation Machine Excellent tool for citing sources in MLA and APA style. Simple fill in the form for the type of source you are citing, i.e. a book, journal article, website, etc., and this tool will show you the way to cite the reference. Be careful of your capitalization.
• Cornell University Library Guide to APA Citation Style

Additional Information for Citing Special Sources

• Ohio Wesleyan University - Citing Maps
• Map Citation Guide from the University of North Carolina
• Citation Fox (citation generator)
• Knight Cite from Calvin College (citation generator)
• Last Updated: May 22, 2024 1:38 PM
• URL: https://libguides.dickinson.edu/citing

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ENGL:4723 Advanced Writing Seminar: Nonfiction - Bonner, Fall 2024: MLA

• Annotated Bibliography

A Brief Intro to MLA

What is it.

• MLA style refers to a specific formatting style created by the Modern Language Association.
• MLA is most commonly used by students and scholars in the humanities and liberal arts when writing papers and citing sources.

How does MLA work?

• MLA Style uses a brief in-text citation and a full citation on a works cited page . 

Where can I find Examples?

• Examples of MLA citations can be found by source in the box to the right on this page or in the print version of the handbook.
• Modern Language Association - MLA Style
• Ask the MLA

What you'll find in the MLA Handbook

MLA Handbook: Ninth Edition

This section covers the basics of how to structure your research project, including margins, page numbering, and inserting lists, tables, and illustrations. These general guidelines are useful but remember to always follow specifics for your course.

Chapter 2: Mechanics of Prose

This extensive section addresses some of the most common and some not-so-common challenges of writing clearly and effectively. This section is a useful refresher on spelling, punctuation, capitalization, and other technical aspects of writing.

Chapter 3: Principles of Inclusive Language

Utilizing inclusive language in your writing demonstrates respect for the identity of individuals and groups while avoiding bias and assumptions. This section provides generalized guidelines for inclusive language use regarding race, ethnicity, religion, gender, sexual orientation, ability, age, and economic or social status. 

Chapter 4: Documenting Sources: An Overview

Academic writing often creates a dialogue with previously created research - make sure that you are properly giving credit to other creators and avoiding plagiarism. This chapter discusses the importance of accurately giving credit to others for their ideas, properly quoting and paraphrasing, and when documentation is not needed. A charge of plagiarism carries severe consequences for your university career. Use this chapter, along with other campus resources, to ensure your writing properly cites the work of others. 

Chapter 5: The List of Works Cited

This section delves deeply into the core elements that make up a citation in MLA style. Using a combination of text, images, and sample citations, this chapter addresses the majority of source types that you will encounter. It also guides writers through determining how to navigate web-based resources, interviews, music, television and movies, and many of the other resources you may utilize in your research.  Note: Citing Indigenous knowledge is not specifically addressed within the MLA handbook. For information on respectfully utilizing Indigenous style principles, refer to Elements of Indigenous Style: A Guide for Writing By and About Indigenous Peoples by Gregory Younging.   

Chapter 6: Citing Sources in the Text

MLA citation style most typically uses brief citations that appear within the text of the document inside parentheses. This chapter also addresses using block quotations, quoting poetry and dialogue, how to cite multiple works by the same author, and technical aspects of in-text citations like punctuation and capitalization.   

Chapter 7: Notes

This chapter briefly addresses the situations when end- or foot-notes may be necessary in your MLA formatted work to provide additional information for your reader, as well as how to properly include them in your writing.   

Appendix 1: Abbreviations

Abbreviations, when used consistently, can smooth the reading experience. Here you'll find lists of words that are usually abbreviated, like US states, or resource types. This appendix includes abbreviations for texts by Chaucer, Shakespeare, and books of the Bible, as well as guidelines for abbreviating the title of any work. 

Appendix 2: Works-Cited-List Entries by Publication Format

This appendix has  over 200   citation examples ! A table of contents in this appendix will help you quickly find examples of how to cite your specific resources.

MLA Citation Examples by Source

•    Articles
•    Audio & Video
•    Books
•   Dictionaries & Encyclopedias
•   Dissertations & Theses
•    In-text Citations
•    Web pages & Social Media
•    Other Source Types

Ask a Librarian

Librarians are available to help you with your questions. Please don't hesitate to contact us with any questions you might have regarding citation styles, citation management, etc.

Ask a question below or contact your subject specialist librarian for more help!

Useful Resources for MLA Citation

• MLA's Online Style Guide
• MLA's In-text Citation Guide

• << Previous: Research
• Next: Annotated Bibliography >>
• Last Updated: Sep 4, 2024 1:24 PM
• URL: https://guides.lib.uiowa.edu/engl4723

• Essay Editor

Acknowledgments in Research Paper: Thanking Those Who Helped

The acknowledgements in research paper are a way to say thank you to the people and groups that helped with the study. This part of the paper lets writers show their thanks and point out the teamwork, support, and guidance they received while doing their research.

Why Include Acknowledgements in a Research Paper?

The acknowledgement section of the paper does more than just talk about the research. It gives writers a chance to thank the many people and groups that helped them write their paper.

While the main part of the paper shows what was found and studied, the acknowledgments in the research paper point out the help from teachers, partners, money givers, schools, and even family and friends who supported the work. This section does a few things:

• It shows that science is often a team effort
• It helps people in the research world appreciate each other
• It makes the research process more personal by showing all the different kinds of help
• It helps make work connections and show kindness
• It can make the writer look good in the research world

In the end, this part of the paper shows how working together and giving back are important for learning new things.

Who Should You Thank?

When thinking about how to write acknowledgments for research paper, include:

• Teachers and advisors who gave advice or helped guide the work
• Partners and co-writers who helped plan, do, or understand the research
• Groups that gave money for the research
• People who took part in collecting information, doing tests, or answering questions
• Tech helpers who assisted with numbers, lab work, or computer programs
• Office workers who helped get resources or gave other help
• Schools or groups that provided tools, machines, or places to work
• Family and friends who gave emotional support or understanding
• Other researchers who gave feedback or helpful criticism

Who Should You Not Thank?

When writing your research paper acknowledgment, be careful not to include:

• People you don't know well or only met briefly
• Unknown reviewers, since their names are often kept secret
• People you don't get along with or have had arguments with
• People with strong political views that might make the research look bad
• Family or friends who didn't really help with the work
• Thank-yous that are too general and don't say exactly what someone did
• Yourself, since the point is to thank other people

How to Format the Acknowledgment Section

When putting together your acknowledgment in research paper, think about this setup:

• Clear title: "Acknowledgments"
• Short opening paragraph saying thanks in general
• Organized list of specific thank-yous, starting with the most important helpers
• Details about what each person did, like helping gather information, understand it, give money, teach, or help with tech stuff
• Professional and formal writing, not using casual words
• Same style of writing throughout
• You can add personal stories or feelings to show how much you appreciate the help

Here's an example:

Acknowledgments

This research couldn't have been done without help from many people and groups. I want to give a big thank you to...

[List of specific thank-yous]

Lastly, I want to thank my family from the bottom of my heart for always being there for me during this work.

Before you finish, read it over carefully to make sure everything is correct, clear, and complete, including the right spelling of names, titles, and where people work.

Helpful Hints for Writing Acknowledgement for Research Paper

Here are ten easy tips to help you figure out how to write acknowledgment for research paper:

• Start by saying a sincere thank you to those who helped
• Clearly name and thank each person, school, or group
• Put the thank-yous in order, with the most important help first
• Keep the writing professional
• Make the thank-yous short and to the point
• Give a quick description of what each person did to help
• Double-check the spelling of names, titles, and where people work
• Include all the important people who helped
• Show personal connections where it makes sense
• Read it over to make sure it's clear and makes sense

Wrapping Up

Writing good acknowledgments in research is a skill that balances saying thanks with being professional. It's a chance to recognize the often hidden support behind your work and to help create a culture of appreciation in the world of research. Well-written acknowledgments for research papers can lead to working together in the future, more people seeing your work, and more support for your ongoing research.

Remember, if you're having trouble figuring out how to write acknowledgment for paper, tools like Aithor can help. Aithor can assist you in creating acknowledgments that are both heartfelt and professional, making sure you give credit where it's due while keeping the scholarly tone of your research paper.

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Purdue Online Writing Lab Purdue OWL® College of Liberal Arts

MLA Formatting and Style Guide

Welcome to the Purdue OWL

This page is brought to you by the OWL at Purdue University. When printing this page, you must include the entire legal notice.

Copyright ©1995-2018 by The Writing Lab & The OWL at Purdue and Purdue University. All rights reserved. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. Use of this site constitutes acceptance of our terms and conditions of fair use.

The following overview should help you better understand how to cite sources using MLA  9 th edition, including how to format the Works Cited page and in-text citations.

Please use the example at the bottom of this page to cite the Purdue OWL in MLA. See also our MLA vidcast series on the Purdue OWL YouTube Channel .

Creating a Works Cited list using the ninth edition

MLA is a style of documentation that may be applied to many different types of writing. Since texts have become increasingly digital, and the same document may often be found in several different sources, following a set of rigid rules no longer suffices.

Thus, the current system is based on a few guiding principles, rather than an extensive list of specific rules. While the handbook still describes how to cite sources, it is organized according to the process of documentation, rather than by the sources themselves. This gives writers a flexible method that is near-universally applicable.

Once you are familiar with the method, you can use it to document any type of source, for any type of paper, in any field.

Here is an overview of the process:

When deciding how to cite your source, start by consulting the list of core elements. These are the general pieces of information that MLA suggests including in each Works Cited entry. In your citation, the elements should be listed in the following order:

• Title of source.
• Title of container,
• Other contributors,
• Publication date,

Each element should be followed by the corresponding punctuation mark shown above. Earlier editions of the handbook included the place of publication and required different punctuation (such as journal editions in parentheses and colons after issue numbers) depending on the type of source. In the current version, punctuation is simpler (only commas and periods separate the elements), and information about the source is kept to the basics.

Begin the entry with the author’s last name, followed by a comma and the rest of the name, as presented in the work. End this element with a period.

Bhabha, Homi K. The Location of Culture. Routledge, 1994.

Title of source

The title of the source should follow the author’s name. Depending upon the type of source, it should be listed in italics or quotation marks.

A book should be in italics:

Henley, Patricia. The Hummingbird House . MacMurray, 1999.

An individual webpage should be in quotation marks. The name of the parent website, which MLA treats as a "container," should follow in italics:

Lundman, Susan. "How to Make Vegetarian Chili." eHow, www.ehow.com/how_10727_make-vegetarian-chili.html.*

A periodical (journal, magazine, newspaper) article should be in quotation marks:

Bagchi, Alaknanda. "Conflicting Nationalisms: The Voice of the Subaltern in Mahasweta Devi's Bashai Tudu." Tulsa Studies in Women's Literature , vol. 15, no. 1, 1996, pp. 41-50.

A song or piece of music on an album should be in quotation marks. The name of the album should then follow in italics:

Beyoncé. "Pray You Catch Me." Lemonade, Parkwood Entertainment, 2016, www.beyonce.com/album/lemonade-visual-album/.

*The MLA handbook recommends including URLs when citing online sources. For more information, see the “Optional Elements” section below.

Title of container

The eighth edition of the MLA handbook introduced what are referred to as "containers," which are the larger wholes in which the source is located. For example, if you want to cite a poem that is listed in a collection of poems, the individual poem is the source, while the larger collection is the container. The title of the container is usually italicized and followed by a comma, since the information that follows next describes the container.

Kincaid, Jamaica. "Girl." The Vintage Book of Contemporary American Short Stories, edited by Tobias Wolff, Vintage, 1994, pp. 306-07.

The container may also be a television series, which is made up of episodes.

“94 Meetings.” Parks and Recreation, created by Greg Daniels and Michael Schur, performance by Amy Poehler, season 2, episode 21, Deedle-Dee Productions and Universal Media Studios, 2010.

The container may also be a website, which contains articles, postings, and other works.

Wise, DeWanda. “Why TV Shows Make Me Feel Less Alone.”  NAMI,  31 May 2019,  www.nami.org/Blogs/NAMI-Blog/May-2019/How-TV-Shows-Make-Me-Feel-Less-Alone . Accessed 3 June 2019.

In some cases, a container might be within a larger container. You might have read a book of short stories on Google Books , or watched a television series on Netflix . You might have found the electronic version of a journal on JSTOR. It is important to cite these containers within containers so that your readers can find the exact source that you used.

“94 Meetings.” Parks and Recreation , season 2, episode 21, NBC , 29 Apr. 2010. Netflix, www.netflix.com/watch/70152031?trackId=200256157&tctx=0%2C20%2C0974d361-27cd-44de-9c2a-2d9d868b9f64-12120962.

Langhamer, Claire. “Love and Courtship in Mid-Twentieth-Century England.” Historical Journal , vol. 50, no. 1, 2007, pp. 173-96. ProQuest, doi:10.1017/S0018246X06005966. Accessed 27 May 2009.

Other contributors

In addition to the author, there may be other contributors to the source who should be credited, such as editors, illustrators, translators, etc. If their contributions are relevant to your research, or necessary to identify the source, include their names in your documentation.

Foucault, Michel. Madness and Civilization: A History of Insanity in the Age of Reason. Translated by Richard Howard , Vintage-Random House, 1988.

Woolf, Virginia. Jacob’s Room . Annotated and with an introduction by Vara Neverow, Harcourt, Inc., 2008.

If a source is listed as an edition or version of a work, include it in your citation.

The Bible . Authorized King James Version, Oxford UP, 1998.

Crowley, Sharon, and Debra Hawhee. Ancient Rhetorics for Contemporary Students. 3rd ed., Pearson, 2004.

If a source is part of a numbered sequence, such as a multi-volume book or journal with both volume and issue numbers, those numbers must be listed in your citation.

Dolby, Nadine. “Research in Youth Culture and Policy: Current Conditions and Future Directions.” Social Work and Society: The International Online-Only Journal, vol. 6, no. 2, 2008, www.socwork.net/sws/article/view/60/362. Accessed 20 May 2009.

Quintilian. Institutio Oratoria. Translated by H. E. Butler, vol. 2, Loeb-Harvard UP, 1980.

The publisher produces or distributes the source to the public. If there is more than one publisher, and they are all are relevant to your research, list them in your citation, separated by a forward slash (/).

Klee, Paul. Twittering Machine. 1922. Museum of Modern Art, New York. The Artchive, www.artchive.com/artchive/K/klee/twittering_machine.jpg.html. Accessed May 2006.

Women's Health: Problems of the Digestive System . American College of Obstetricians and Gynecologists, 2006.

Daniels, Greg and Michael Schur, creators. Parks and Recreation . Deedle-Dee Productions and Universal Media Studios, 2015.

Note : The publisher’s name need not be included in the following sources: periodicals, works published by their author or editor, websites whose titles are the same name as their publisher, websites that make works available but do not actually publish them (such as  YouTube ,  WordPress , or  JSTOR ).

Publication date

The same source may have been published on more than one date, such as an online version of an original source. For example, a television series might have aired on a broadcast network on one date, but released on  Netflix  on a different date. When the source has more than one date, it is sufficient to use the date that is most relevant to your writing. If you’re unsure about which date to use, go with the date of the source’s original publication.

In the following example, Mutant Enemy is the primary production company, and “Hush” was released in 1999. Below is a general citation for this television episode:

“Hush.” Buffy the Vampire Slayer , created by Joss Whedon, performance by Sarah Michelle Gellar, season 4, Mutant Enemy, 1999 .

However, if you are discussing, for example, the historical context in which the episode originally aired, you should cite the full date. Because you are specifying the date of airing, you would then use WB Television Network (rather than Mutant Enemy), because it was the network (rather than the production company) that aired the episode on the date you’re citing.

“Hush.” Buffy the Vampire Slayer, created by Joss Whedon, performance by Sarah Michelle Gellar, season 4, episode 10, WB Television Network, 14 Dec. 1999 .

You should be as specific as possible in identifying a work’s location.

An essay in a book or an article in a journal should include page numbers.

Adiche, Chimamanda Ngozi. “On Monday of Last Week.” The Thing around Your Neck, Alfred A. Knopf, 2009, pp. 74-94 .

The location of an online work should include a URL.  Remove any "http://" or "https://" tag from the beginning of the URL.

Wheelis, Mark. "Investigating Disease Outbreaks Under a Protocol to the Biological and Toxin Weapons Convention." Emerging Infectious Diseases , vol. 6, no. 6, 2000, pp. 595-600, wwwnc.cdc.gov/eid/article/6/6/00-0607_article. Accessed 8 Feb. 2009.

When citing a physical object that you experienced firsthand, identify the place of location.

Matisse, Henri. The Swimming Pool. 1952, Museum of Modern Art, New York .

Optional elements

The ninth edition is designed to be as streamlined as possible. The author should include any information that helps readers easily identify the source, without including unnecessary information that may be distracting. The following is a list of optional elements that can be included in a documented source at the writer’s discretion.

Date of original publication:

If a source has been published on more than one date, the writer may want to include both dates if it will provide the reader with necessary or helpful information.

Erdrich, Louise. Love Medicine. 1984. Perennial-Harper, 1993.

City of publication:

The seventh edition handbook required the city in which a publisher is located, but the eighth edition states that this is only necessary in particular instances, such as in a work published before 1900. Since pre-1900 works were usually associated with the city in which they were published, your documentation may substitute the city name for the publisher’s name.

Thoreau, Henry David. Excursions . Boston, 1863.

Date of access:

When you cite an online source, the MLA Handbook recommends including a date of access on which you accessed the material, since an online work may change or move at any time.

Bernstein, Mark. "10 Tips on Writing the Living Web." A List Apart: For People Who Make Websites, 16 Aug. 2002, alistapart.com/article/writeliving. Accessed 4 May 2009.

As mentioned above, while the MLA handbook recommends including URLs when you cite online sources, you should always check with your instructor or editor and include URLs at their discretion.

A DOI, or digital object identifier, is a series of digits and letters that leads to the location of an online source. Articles in journals are often assigned DOIs to ensure that the source is locatable, even if the URL changes. If your source is listed with a DOI, use that instead of a URL.

Alonso, Alvaro, and Julio A. Camargo. "Toxicity of Nitrite to Three Species of Freshwater Invertebrates." Environmental Toxicology , vol. 21, no. 1, 3 Feb. 2006, pp. 90-94. Wiley Online Library, doi: 10.1002/tox.20155.

Creating in-text citations using the previous (eighth) edition

Although the MLA handbook is currently in its ninth edition, some information about citing in the text using the older (eighth) edition is being retained. The in-text citation is a brief reference within your text that indicates the source you consulted. It should properly attribute any ideas, paraphrases, or direct quotations to your source, and should direct readers to the entry in the Works Cited list. For the most part, an in-text citation is the  author’s name and the page number (or just the page number, if the author is named in the sentence) in parentheses :

When creating in-text citations for media that has a runtime, such as a movie or podcast, include the range of hours, minutes and seconds you plan to reference. For example: (00:02:15-00:02:35).

Again, your goal is to attribute your source and provide a reference without interrupting your text. Your readers should be able to follow the flow of your argument without becoming distracted by extra information.

How to Cite the Purdue OWL in MLA

Entire Website

The Purdue OWL . Purdue U Writing Lab, 2019.

Individual Resources

Contributors' names. "Title of Resource." The Purdue OWL , Purdue U Writing Lab, Last edited date.

The new OWL no longer lists most pages' authors or publication dates. Thus, in most cases, citations will begin with the title of the resource, rather than the developer's name.

"MLA Formatting and Style Guide." The Purdue OWL, Purdue U Writing Lab. Accessed 18 Jun. 2018.

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• Open access
• Published: 02 September 2024

Fault diagnosis method for oil-immersed transformers integrated digital twin model

• Haiyan Yao 1 ,
• Xin Zhang 2 ,
• Qiang Guo 1 ,
• Yufeng Miao 1 &
• Shan Guan 3  

Scientific Reports volume  14 , Article number:  20355 ( 2024 ) Cite this article

Metrics details

• Electrical and electronic engineering
• Mechanical engineering

To address the problems of low accuracy in fault diagnosis of oil-immersed transformers, poor state perception ability and real-time collaboration during diagnosis feedback, a fault diagnosis method for transformers based on the integration of digital twins is proposed. Firstly, fault sample balance is achieved through Iterative Nearest Neighbor Oversampling (INNOS), Secondly, nine-dimensional ratio features are extracted, and the correlation between dissolved gases in oil and fault types is established. Then, sparse principal component analysis (SPCA) is used for feature fusion and dimensionality reduction. Finally, the Aquila Optimizer (AO) is introduced to optimize the parameters of the Kernel Extreme Learning Machine (KELM), establishing the optimal AO-KELM diagnosis model. The final fault diagnosis accuracy reaches 98.1013%. Combining transformer digital twin models, real-time interaction mapping between physical entities and virtual space is achieved, enabling online diagnosis of transformer faults. Experimental results show that the method proposed in this paper has high diagnostic accuracy and strong stability, providing reference for the intelligent operation and maintenance of transformers.

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Discernment of transformer oil stray gassing anomalies using machine learning classification techniques

Introduction.

The transformer, as the hub of power systems, its health status directly impacts the stability and reliability of the electrical system's operation. Therefore, the precise management of a transformer's health status is paramount to ensuring the steadfast and secure operation of the power grid 1 .

Presently, the technology of Dissolved Gas Analysis (DGA) is extensively employed in the monitoring and identification of faults within oil-insulated transformers 2 , 3 , primarily encompassing: the IEC triad ratio method 4 , the Rogers quadruple ratio method 5 , and the DUVAL triangle technique 6 . Despite their simplicity of operation, these approaches lack the depth of representation for fault characteristics and are limited by their capabilities, resulting in a blurred and indistinct encoding boundary, thereby leading to a low accuracy rate in fault recognition 7 . With the rapid advancement of artificial intelligence, eminent scholars have integrated machine learning with DGA technology, achieving notable results in the field of transformer fault detection. The literature 8 optimizes the support vector machine parameters through the refinement of the scalar search algorithm, thereby augmenting both the convergence velocity and the diagnostic precision of the methodology. The literature 9 proffers an SE-ELM diagnostic method, whose efficacy was validated through the verification across various datasets. The literature 10 enhances the particle swarm optimization algorithm through the dynamic adjustment of inertial weights and acceleration factors, iteratively optimizing the parameters of XGBoost, thereby augmenting the model's classification acumen. Additionally, methods such as Convolutional Neural Networks 11 , 12 , Long Short-Term Memory Networks 13 , 14 , 15 , LightGBM 16 , and the Capsule Network 17 are extensively employed.

With the advancement of big data and the Internet of Things (IoT) technologies, the Digital Twin (DT) 18 technology has paved a new path for enhancing the efficiency of equipment health management. The core concept is to construct a holographic virtual twin model in the digital realm, utilizing advanced technologies such as intelligent sensing and data transmission, which accurately, comprehensively, and in real-time reflect the evolution of physical devices, achieving intelligent control over entities 19 , 20 , 21 . This technology has been extensively utilized in various sectors including aerospace, manufacturing, and healthcare.

In the field of transformer fault diagnosis, scholars both domestically and internationally have carried out extensive research. Referencing 22 , the study proposed a method for constructing a dual-driving twin model integrating data and models, focusing on 10 kv oil-immersed transformers. This approach enables the synchronization between the actual operating conditions of the transformer and the digital twin center. Referencing 23 , a digital twin fault diagnosis model was constructed based on the mechanism model and data model of transformers. Five characteristic gases extracted from DGA data were selected as input feature vectors for a CNN. Experimental results showed that the 1D-CNN model established in this study responded rapidly, had a short training time, and achieved high accuracy, thus validating the effectiveness of the model. Referencing 24 , a fault diagnosis model based on digital twin was constructed for transformers, taking into account their structural characteristics and operational traits. By optimizing the smoothing factor δ in a probabilistic neural network through differential evolution algorithm, the diagnostic accuracy reached an impressive 96.7%, enabling precise monitoring of the transformer's actual operating state. Reference 25 conducts a statistical analysis of the operating data and state information quantity of power transformers, proposes a framework for a state evaluation system and fault detection system based on GCA-CNN, and verifies with 2000 real data cases that the model has higher accuracy and evaluation and detection effects. The literature 26 establishes a high-fidelity simulation model of transformers to accurately simulate winding currents and the temperatures of different components, which can be used for the identification of early faults. However, the aforementioned research is only focused on a single dissolved gas in oil or vibration signal as the basis for fault diagnosis, but there are many factors affecting transformer faults. In the future, it may be possible to combine multi-source data for comprehensive judgment.

In light of the above context, this paper proposes a fault diagnosis method for oil-immersed transformers that integrates a digital twin model. The main contributions of the paper are divided into several parts. Part 1 mainly elaborates on the research background of the paper and the future research direction. Part 2 establishes a transformer digital twin framework, based on geometric, physical, behavioral, and rule models, to achieve interaction mapping between the virtual entity and the physical entity. Part 3 introduces the methods used in the paper, providing theoretical support for the establishment of an accurate and efficient fault diagnosis model. Part 4 addresses the issue of imbalanced small sample data that can easily lead to misjudgment of minority class samples, deeply explores the correlation between dissolved gases in oil and fault types, and eliminates the 'dimensionality catastrophe' problem, using instance data to obtain diagnostic results. Part 5 discusses and analyzes different sampling methods, different features, and different diagnostic models. Part 6 summarizes the entire paper.

Transformer fault diagnosis model fusing digital twin

Transformer digital twin framework.

This article takes a 400kV oil-immersed transformer as the research object and establishes a transformer digital twin integrated digital twin technology. The constructed digital twin framework mainly includes: physical space, twin body, twin data layer and application service layer 27 , as shown in Fig.  1 .

Transformer digital twin framework.

In the process of building a digital twin, the geometric model is the foundation for creating the digital twin model. Three-dimensional software such as UG and SolidWorks are used to comprehensively describe the solid model in terms of geometric dimensions, material properties, and assembly relationships. Based on prior knowledge, physical properties, and operating mechanisms, the geometric model is analyzed and tested for magnetic field, structure, and other modeling aspects, fully reflecting the intrinsic nature and operating mechanism of the transformer. Heterogeneous data from multiple sources, such as dissolved gas in oil and acoustic vibration signals, are collected using state-aware devices. Artificial intelligence algorithms integrated in the behavior model are used for processing and analysis. The derived data generated from simulation calculations are fed back to the mechanism model in real-time. At the same time, simulation data, state-aware data, as well as transformer's full life cycle process data, maintenance records, and computed derived data collectively form the twin database. Through data communication protocols and interfaces, real-time updates and interactive control between the physical entity and the digital twin are achieved, enabling visual description, real-time monitoring, analysis, diagnosis, and intelligent decision-making for the physical transformer. This provides new ideas for improving the safety and reliable operation of power transmission and transformation equipment.

The five-dimensional model of digital twin

The present work is founded on the five-dimensional model proposed by Tao Fei from Beijing Aerospace University 28 , culminating in the creation of a digital twin for transformers, as exemplified by Eq. ( 1 ).

where: PE denotes the physical entity of the transformer, VE represents the virtual entity, SS signifies data, algorithms and models of the digital twin, DD stands for the twinning data of the transformer, and CN symbolizes the interaction and communication among the various components.

The acronym PE stands for transformer physical entity, an ensemble of components including the core, windings, tap-changer, and cooling equipment, it caters to the perception of contact or non-contact by state-sensing devices, embodying the interactive and responsive essence of an objective presence.

The SS represents the process of integrating data and models generated by the digital twin transformer system, thereby facilitating comprehensive monitoring of entities, diagnostic analysis of equipment failures, and predictive maintenance.

VE represents the twin model of the virtual realm, establishing the fundamental groundwork for mapping the virtual to the real. The specific composition is delineated by the formula ( 2 ) shown:

where: Gv represents the geometric model, which uses 3D modeling software to create a comprehensive description of the geometric features of physical entities; Pv represents the physical model, which describes the physical properties and operating mechanisms of electrical equipment; Bv represents the behavior model, which combines artificial intelligence algorithms to create Bv; Rv represents the rule model, which mainly includes expert experience and rule inference based on processed historical data for optimization and deduction.

DD represents twin data, which dynamically stores relevant data of PE/VE/SS, and is an important prerequisite for ensuring intelligent operation and maintenance of transformers. The specific representation is shown in formula ( 3 ):

where: Dp refers to the dynamic factor data collected through the state-aware device; Dv refers to the running parameters in the virtual model; Ds mainly refers to the functional and business service data; Dk includes expert experience, industry rules in the transformer field, and usage guidelines, etc. Df refers to the integrated transformation, interactive fusion, and other derived data of the above-mentioned data.

CN represents the data connection part, which is crucial for ensuring the interaction and updating of the elements in the digital twin model. Through data interfaces, communication protocols, etc., efficient transmission and utilization of data in the digital twin system can be achieved, enabling seamless communication and connectivity among different parts of the model. The interactive relationships of the five dimensions in the digital twin model are shown in Fig.  2 .

Transformer digital twin five-dimensional model connection relationship.

Transformer fault diagnosis model based on optimized extreme learning machine

Iterative nearest neighbor oversampling algorithm.

The iterative neighborhood oversampling 29 algorithm is a sampling method designed to tackle class imbalance issues, with its principal tenet being the selection of a multitude of class-specific samples as neighbors, and then traversing all k data points within this category, scouring for the most recent unlabeled instance within each label data subset of said category until the dataset balances out or approaches close to it. Here follow the specific steps:

Assume the samples in the dataset for each tag to be \({\text{r}} = \left\{ {r_{1} ,r_{2} , \cdots ,r_{j} , \cdots ,r_{a} } \right\}\) , with \(r_{j} \left( {j = 1,2, \cdots a} \right)\) denoting the number of samples contained within category j . Define the sample set's imbalance factor, utilizing the standard deviation \({\text{var}} \left( r \right)\) to symbolize the dispersal of various types of samples within the dataset, as illustrated in Eq. ( 4 ):

where: \(\mathop r\limits^{ - } = \frac{1}{a}\sum\limits_{j = 1}^{a} {r_{j} }\) .

Based on the philosophy of greedy search, endeavor to identify a multitude of particular sub-samples, with the process detailed in formula ( 5 ):

where: \(x_{j}\) represents the labeled data in category j . If \(x_{\max k}\) is the classification boundary, remove it and select the next nearest neighbor. Then, label it as category j , remove it from the unlabeled data set \(X_{U}\) , add it to the labeled data set \(X_{L}\) , and set \(r_{j} = r_{j} + 1\) . Recalculate the imbalance degree until the preset value is reached, and stop iterating.

Extreme learning machine algorithm

The Kernel Extreme Learning Machine (KELM) 30 is based on a single hidden layer feedforward neural network. It introduces a kernel function on top of the ELM algorithm, which maps low-dimensional data to a high-dimensional feature space, resulting in a model with stronger generalization and robustness. The specific steps are as follows:

Assume we are provided with N samples represented as \(\left\{ {\left( {{\text{x}}_{{\text{i}}} ,t_{i} } \right)} \right\}_{i = 1}^{N}\) , where \(x_{i} = \left[ {x_{i1} ,x_{i2} , \cdots ,x_{in} } \right]^{T} \in R^{n}\) and \(t_{i} = \left[ {t_{i1} ,t_{i2} , \cdots ,t_{im} } \right]^{T} \in R^{n}\) denote the input vector and output function of the model respectively. In the context of a neural network with k hidden layers and an activation function \(g\left( x \right)\) , the number of hidden nodes is L , and the ELM model can be articulated by the formula shown in Eq. ( 6 ):

where: \(\beta_{j} = \left[ {\beta_{j1} ,\beta_{j2} , \cdots ,\beta_{jL} } \right]^{T} \left( {j = 1,2, \cdots ,L} \right)\) denotes the output weight value connecting the j th implicit layer node with the output layer node. Among these, \(H = \left\{ {h_{ij} } \right\}\left( {i = 1,2, \cdots ,N;j = 1,2, \cdots ,L} \right)\) represents the output matrix of the hidden layer, and H denotes the jth column of the input \(x_{1} ,x_{2} , \cdots ,x_{n}\) corresponding to the jth hidden layer node. Within H, the jth row corresponds to the output vector of \(x_{i}\) .

Using the least squares method to obtain the output weight values, as shown in formula ( 7 ):

In the formula, \(H{\prime}\) represents the generalized inverse matrix of the hidden layer output matrix H .

Introducing the kernel function mitigates the issue of randomly generated input weights and bias values, exemplified by the KELM weight output formula ( 8 ):

The KELM output function as expressed in formula ( 9 ):

When \(h\left( x \right)\) remains unknown, the kernel function matrix is represented by formula ( 10 ):

In the equation, \(K\left( {x_{i} ,x_{j} } \right)\) denotes the nuclear function, represented as:

The KELM model's output function expression is delineated in formula ( 12 ):

Sparse principal component analysis

The sparse principal component analysis 31 is a method that builds upon the principal component analysis algorithm by incorporating the LASSO penalty term, thereby enabling the matrix to be sparsely populated. By solving the regression coefficient matrix, it further transforms PCA into an optimization problem aimed at finding the optimal set of coefficients for regression. Compared to traditional PCA, SPCA excels in effectively managing the sparsity within high-dimensional data, yielding results that are more interpretative.

The SPCA algorithm is resolve into two segments: the first entails calculating the principal components via PCA; the second entails enhancing the LASSO penalty term to render the obtained solution sparse. Here follow the specific steps:

Given a \({\text{n}} \times m\) -variant dataset X, the feature decomposition upon normalization treatment, as expounded upon in formula ( 13 ):

In the equation, \(\Lambda \in R^{m \times m}\) represents a diagonal matrix of eigenvalues, arranged in descending order. \(\Lambda \in R^{m \times m}\) is a unitary matrix with column vectors as load vectors.

Select the first k columns of the load matrix \(P \in R^{m \times k}\) , compute the score matrix T , as shown in Eq. ( 14 ):

Projecting T onto X yields a new matrix \(\mathop X\limits^{ \wedge }\) that encompasses information from the corresponding principal component; the difference with X is denoted as E , as illustrated in formula ( 15 ), ( 16 ):

The solution of the SPCA first reverts to the PCA model. The formula ( 15 – 16 ) yields the expression ( 17 ):

Ensure the main component is as near to the original data as possible, that is,it mandates E'sminimalism. Therefore, the principal component seeks resolution through formula ( 18 ):

In the equation, \(\mathop P\limits^{ \wedge }\) is the solution to the minimum value of the principal matrix P .

The vectors sought by PCA are all non-zero; thus, the sparse solution is achieved by incorporating the LASSO penalty term, thereby mitigating the overfitting issue in PCA. The solution formula for sparse principal components, as displayed in formula ( 19 ), is illustrated:

In this equation, matrix A denotes the expected demand matrix to be sought, while matrix B represents the demand matrix expected under the regression problem. A and B represent the \(m \times k\) matrix, \(\mathop A\limits^{ \wedge }\) and \(\mathop B\limits^{ \wedge }\) the matrices to be solved for minimizing values of A and B; they are subject to the constraints \(b_{j} \propto P_{j}\) , \(\lambda\) and \(\lambda_{1,j}\) being the penalty coefficients, and must adhere to \(\lambda > 0\) . The adjusted variance, as expressed in formula ( 20 ), is indicative of:

In the equation, the diagonal matrix interpreting variance is delineated, with \(\mathop P\limits^{ \wedge }\) representing the load matrix following the coefficients. Model contribution lies articulated in formula ( 21 ):

Transformer fault diagnosis model process

This article, established on the premise of transformer fault imbalance within small sample sets, aims at achieving real-time and precise diagnosis through the establishment of a diagnostic model and a determined diagnostic process. The specific diagnostic process is illustrated in Fig.  3 . The article employs the AO-KELM model as the diagnostic model, erecting a diagnostic process that integrates offline model training with online fault identification.

Transformer fault diagnosis model based on optimized kernel extreme learning machine.

⑴ Train the model offline

The article delves into the offline model training segment from three perspectives: data preprocessing, feature extraction, and model recognition.

Step 1: the preprocessing segment encompasses data INNOS's oversampling and normalization treatment. Collect the gathered DGA samples through INNOS for augmenting the minority class samples, followed by normalization treatment.

Step 2: the feature extraction section encompasses the establishment of ratio signature generation and the integration of SPCA for fusion dimensionality reduction. First, construct a multidimensional discriminant signature, delving deeply into the correlation between the ratio of dissolved gas content in oil and the type of fault. Subsequently, employ SPCA for feature fusion to acquire the optimal principal component, thereby removing redundant information, and divide the training set, validation set, and test set proportionally.

Step 3: the model identification segment encompasses the training and validation of the model. Utilizing the AO algorithm to optimize the regularization parameters C and the kernel functions within the KELM model, one verifies the model's accuracy through validation set on each iteration. Should the discrepancy between consecutive training sessions fall beneath 5%, the model training continues; otherwise, the model retraining commences anew until the prerequisite conditions are met. The ultimate establishment of the AO-KELM optimal diagnostic model.

⑵ Online fault diagnosis

Normalize the samples collected in real-time to handle and construct multi-dimensional features, employing an unencoded ratio method to input into an optimal diagnosis model directly following optimal principal component projection, thereby achieving swift recognition of transformer fault. Although the computational time for offline model training is accordingly elevated, it is merely necessary to undergo training once, with the aim of achieving online recognition and diagnosis of transformer faults as data from real-time monitoring continues to be inputted.

Case study analysis

Data source and normalization processing.

Transformer insults are exacerbated by thermal electrochemical action, causing the decomposition of internal insulating materials and the dissolution of various hydrocarbon gases within the insulation oil. Distinct characteristics of gas dissolved in oil under varying fault types exist; research has demonstrated that diagnostic and classification of faults can be achieved through the use of DGA techniques 32 . Consequently, these five gas contents are utilized as a basis for transformer fault diagnosis in this article.

The article selected a comprehensive sample of 337 monitoring data from a particular power supply company, dividing the operating status of transformers into categories such as normal, moderate heat overload, high temperature overload, high energy discharge, low energy discharge, and local discharge, each represented by labels 1 through 6. Each type of fault is augmented with specific characteristic gases including H 2 , CH 4 , C 2 H 4 , C 2 H 6 , and C 2 H 2 ; the exact number of samples for each category is detailed in Table 1 . The data reveals that the majority of samples fall into the category of normal, comprising 35.63% of the total. Low-energy discharge and local discharge types account for 5.55% and 9.78% respectively, with a maximum disparity reaching 5.1:1. Such imbalanced data is prone to misidentifying samples of the minority class as normal, thereby impacting recognition accuracy. Therefore, this paper employs the INNOS algorithm to augment the minority class samples, achieving a balance in sample categories.

To manifest the disparities between data prior to and after sampling, a principal component analysis is conducted upon the sample data from before and after said sampling process. Subsequently, the first two principal components are selected for visualizing the data of various types both before and after said sampling, as illustrated in Fig.  4 . In Fig.  4 , it becomes apparent that the data distribution trends for various types of faults, prior to and after the adoption of the INNOS sampling method, are identical, thereby underscoring the viability of the INNOS sampling approach.

Scatter plot of INNOS samples.

Transformer malfunction signature composition

Considering the substantial disparities among the various volatile gases, a preliminary normalization is required for each gas's abundance, as illustrated in Eq. ( 22 ):

In the equation: \(x_{i}\) and \(x_{{\text{i}}}^{*}\) represent features pre-normalized; \({\text{x}}_{{{\text{i}}\max }}\) and \({\text{x}}_{{{\text{i}}\min }}\) indicate the original minimal and maximum values.

The method of unencoded ratio analysis 33 is but one among numerous techniques widely employed, utilizing the percentage ratio of key gases to either the total gas or the hydrocarbon concentration can profoundly illustrate the interconnectedness between characteristic gases and types of failures. For instance, the ratio of a singular gas to the total hydrocarbon concentration provides a more conclusive indicator of the interplay between diverse fault types; the concentrations of C 2 H 4 and CH 4 can effectively demarcate local discharge from discharge with overheating diagnosis; the percentage composition of C 2 H 2 can determine whether a transformer has experienced thermal failure, among other determinations. The construction of this paper is predicated on the integration of pertinent literature, establishing a nine-dimensional candidate ratio signature for transformer fault diagnosis 31 , as delineated in Table 2 , wherein THC = CH 4  + C 2 H 4  + C 2 H 6  + C 2 H 2 , and ALL = H 2  + CH 4  + C 2 H 4  + C 2 H 6  + C 2 H 2 .

Dimensionality reduction through feature parameter fusion

To avoid the redundancy of fault-related feature information within the samples and to enhance the efficiency and precision of the diagnostic model, the SPCA method was employed for the integration of the derived rational features. The cumulative explicable variance contribution rate of each principal component is depicted in Fig.  5 . It is evident from Fig.  5 that the cumulative variance contribution rate for the first six principal components reaches 90.4419%, indicating that the first five principal components can achieve more than 90% of the ability expressed by all the principal components. Hence, selecting these five principal components as inputs for the transformer fault diagnosis model is warranted.

Cumulative variance contribution rate.

Transformer malfunction diagnosis outcomes

The fused features derived from the SPCA extraction are delineated in a ratio of 6:2:2 to be divided into training, testing, and validation datasets. The regularization parameters C within KELM determine the learning capacity of the model and its diagnostic precision; in this paper, we employ the AO optimization algorithm to optimize C, with an introduction of the AO algorithm as delineated in literature 34 , 35 , culminating in the establishment of a diagnostic model based on SPCA-AO-KELM. Figure  6 delineates the confusion matrix diagram of the transformer fault diagnosis. It is evident from Fig.  6 that within the test set of 158 samples, 155 were correctly diagnosed, representing a total correct rate of 98.1013%. The accuracy rates for normal, high-temperature overheating, and low-energy discharge diagnoses are 100%, one case of misjudgment was found in medium–low temperature overheating, high-energy discharge, and partial discharge.

Transformer fault diagnosis results.

However, the precision of diagnostic accuracy alone cannot comprehensively nor efficaciously evaluate the impact of rare class faults on classification performance 36 , 37 . In this paper, we introduce classification model performance evaluation metrics derived from confusion matrices, employing accuracy (R), precision (P), and F1-score as the core components of our evaluation system. The veracity of diagnostic models for identifying various faults is assessed by the accuracy rate, the sensitivity of the model in recognizing a variety of faults is evaluated by the coverage rate, while the F1 score derived from the amalgamation of precision and recall reflects the model's classification performance amidst sample imbalance, with specific formulas denoted in the literature displayed here. The model's precision, recall, and F1-score derived from the computed graph in Fig.  6 respectively stand at 0.9816, 0.9825, and 0.9820, further underscoring the model's high fault detection accuracy and its stable nature.

Results and discussions

Comparison and analysis of different sampling methods.

To verify the effectiveness of the new samples synthesized based on INNOS in improving the accuracy of transformer fault diagnosis, this paper uses unbalanced data set, random oversampling, SMOTE, and ADASYN oversampling algorithms for sample augmentation, and the diagnostic results are shown in Fig.  7 . The red dots in the figure represent the samples that are correctly classified in the test set, while the circles represent the samples of the true class, and the scattered dots represent the samples that are misclassified as other classes. The more scattered sample points, the higher the misclassification rate. In Fig.  7 d, the diagnostic accuracy of the original unbalanced data set without balancing processing is only 88.4058%, indicating that due to the imbalance of data in each fault category, the training of the diagnostic model is insufficient, and it is easy to misclassify minority class samples as majority class samples during classification recognition. After balancing the data set using different sampling methods, the misclassification rate of the samples decreases. The sampling method used in this paper improves the diagnostic accuracy by 7.7967%, 2.5316%, and 1.8987% compared to ADASYN, SMOTE, and random oversampling, respectively, indicating that the INNOS sampling method can effectively solve the problem of low diagnostic accuracy caused by data imbalance.

Diagnostic results under different sampling methods.

Qualitative and quantitative analysis with integrated features

To demonstrate the effectiveness of the SPCA feature fusion method, this study conducted analysis from two perspectives: qualitative observation and quantitative analysis. Firstly, PCA, KPCA, and SPCA were used to extract features from the constructed ratio signs. The cumulative variance contribution rate threshold was set at 90%, and the obtained principal component information is detailed in Table 3 . LASSO penalty term was introduced based on PCA to constrain some loading vectors to zero, resulting in a loss of variance contribution rate. From the data in the table, it can be seen that the contribution rate of SPCA principal components is slightly lower than that of PCA and KPCA, effectively removing redundant information in the ratio features and providing a valid data foundation for subsequent classification and recognition.

Furthermore, for the above feature extraction methods, quantitative calculations were performed. The fused features extracted by the 9-dimensional joint feature, PCA, KPCA, and SPCA were input into the diagnostic model for comparative analysis, as shown in Fig.  8 . From Fig.  8 a–d, it can be observed that the diagnostic accuracy is significantly improved after feature extraction. Figure  8 a has a higher accuracy compared to Fig.  8 b and c, which validates the superiority of the SPCA feature extraction method.

Diagnostic outcomes under various characteristics.

Analysis of contrastive diagnostic models

To explore the diagnostic performance of the models, three diagnostic models, ELM, KELM, and AO-ELM, were constructed for horizontal comparison. The diagnostic results are shown in Table 4 . From the perspective of a single model, the introduction of a kernel function improved the diagnostic accuracy and evaluation indicators of ELM. From the perspective of optimization algorithms, the diagnostic capability of fault recognition was effectively improved after parameter optimization using the AO algorithm.

On the other hand, the extracted integration features are respectively inputted into the POA-SVM model proposed in Literature 38 , the SSA-ELM model suggested in Literature 39 , and the PSO-BiLSTM model introduced in Literature 40 for longitudinal comparison. To circumvent the chances of chance, each model is subjected to ten-fold cross-validation, as manifested in Table 5 . It is evident from Table 5 that, under conditions where the input features remain identical, the AO-KELM outperforms both the POA-SVM and POA-SVM by elevating the average accuracy by 3.23% and 2.64%, respectively, while the PSO-BiLSTM lags behind with a mere 1.8% increase in accuracy. This clearly signifies the robust stability of the AO-KELM model and its formidable classification capabilities.

The paper introduces an oil-immersed transformer fault diagnosis method that integrates digital twin models, providing validation through case studies, leading to the conclusions below:

Build a twin mechanism model based on geometric, physical, rule, and behavior models, use real-time data to drive the fusion of data and mechanism models, complete real-time mapping between physical entities and virtual entities, and use visualization technology to express the twin in multiple dimensions, achieve intelligent diagnosis, health monitoring, and optimization decision-making for the transformer entity.

Proposed a transformer fault diagnosis model based on optimized kernel extreme learning machine, which solves the problem of misjudgment of minority class samples caused by unbalanced small samples, effectively extracts fusion features, establishes the optimal AO-KELM classifier, and achieves an accuracy of 98.1013%. By comparing with different diagnostic models, the classification performance and stability of the proposed method are verified.

Data availability

The datasets generated and/or analysed during the currentstudy are not publicly availabledue [REASON WHY DATA ARENOT PUBLlC] but are availablefrom the corresponding authoron reasonable request. E-mail:[email protected].

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Unveiling the deterioration formation process of the rammed earth city wall site of the Ancient City of Pingyao, a World Heritage Site: occurrence, characterizations, and historic environmental implications

• Published: 02 September 2024
• Volume 16 , article number  156 , ( 2024 )

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• Xiangling Bai 1 ,
• Bin He 1 , 2 ,
• Diyue Zhang 1 ,
• Yingxin Wang 1 ,
• Xiaohong Bai 1 ,
• Fuli Ma 1 &
• Pengju Han 1  

Large, immovable rammed earth buildings in UNESCO World Cultural Heritage sites are at serious risk of disaster due to environmental changes. In this study, the rammed earth city walls (REWs) located in the Ancient City of Ping Yao, a World Cultural Heritage site, affected by heavy precipitation in early October 2021, were used as the research object. The study aimed to specify the details of deterioration through multiple indicator data collection, semi-quantitatively evaluate the degree of deterioration of REWs, and investigate the causes of typical deterioration in REWs with different spatial distributions under the influence of heavy precipitation. Based on the current research and experimental data, and considering the mode of action and form of deterioration, a classification system for the landslide-like collapses of REWs under the influence of precipitation was constructed. Factors such as the influence of heavy precipitation and the REWs' intrinsic features resulted in significant variations in structural properties and deterioration development of REWs with different spatial distribution characteristics. Finally, based on the research in this paper and the conservation ideology of cultural relics that respects the original and minimizes intervention, we propose protection recommendations for the daily management and conservation of the REWs to provide guidance for future research.

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Acknowledgements

We thank the Culture and Tourism Bureau of Jinzhong City for its assistance in assembling the historical data of the rammed earth walls in this study. We thank the Shanxi Key Laboratory of Civil Engineering Disaster Prevention and Control (202104010910025, Shanxi Key Laboratory Project) and the Geotechnical Engineering Research Centre of the Ancient City of Pingyao (Technology Development Service Project) for the assistance in this study.

The research was supported by the Shanxi Key Laboratory of Civil Engineering Disaster Prevention and Control (202104010910025, Shanxi Key Laboratory Project) and the Geotechnical Engineering Research Centre of the Ancient City of Pingyao (Technology Development Service Project).

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Xiangling Bai designed the research in close collaboration with Pengju Han and with support from Xiaohong Bai, Bin He and Fuli Ma. Xiangling Bai conducted the analysis and analysed the results in collaboration with Diyue Zhang and Hao Li. Xiangling Bai wrote the manuscript with contributions from Pengju Han, Bin He. and Yingxin Wang. All authors reviewed and edited the manuscript.

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Bai, X., He, B., Zhang, D. et al. Unveiling the deterioration formation process of the rammed earth city wall site of the Ancient City of Pingyao, a World Heritage Site: occurrence, characterizations, and historic environmental implications. Archaeol Anthropol Sci 16 , 156 (2024). https://doi.org/10.1007/s12520-024-02058-6

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