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References in Research – Types, Examples and Writing Guide

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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

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References: How to Cite and List Correctly

First Online: 25 February 2021

Cite this chapter

C. George Thomas 2

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When we write an essay, research paper, thesis, or book, it is normal to include information from the work of others or support our arguments by reference to other published works. All such academic documents draw heavily on the ideas and findings of previous and current researchers available through various sources such as books, journals, theses, newspapers, magazines, government reports, or Internet sources. In all these cases, proper referencing is essential in order to ensure easy retrieval of information. Referencing is the name given to the method of showing and acknowledging the sources from which the author has obtained ideas or information.

Everything deep is also simple and can be reproduced simply as long as its reference to the whole truth is maintained. But what matters is not what is witty but what is true. Albert Schweitzer (1875–1965)

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Introduction
Parenthetical vs. narrative
Multiple authors

Missing information

Sources to include

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APA referencing guidelines

APA Style is widely used by students, researchers, and professionals in the social and behavioral sciences. The Scribbr APA Reference Generator automatically generates accurate references and in-text citations for free.

This referencing guide outlines the most important referencing guidelines from the 7th edition APA Publication Manual (2020). Scribbr also offers free guides for the older APA 6th edition , Vancouver Style , and Harvard Style .

APA in-text citations

In-text citations are brief references in the running text that direct readers to the full reference entry at the end of the paper. You include them every time you quote or paraphrase someone else’s ideas or words.

An APA in-text citation consists of the author’s last name and the year of publication (also known as the author-date system). If you’re citing a specific part of a source, you should also include a locator such as a page number or timestamp. For example: (Smith, 2020, p. 170) .

Parenthetical vs. narrative citation

The in-text citation can take two forms: parenthetical and narrative. Both types are generated automatically when citing a source with Scribbr’s APA Citation Generator.

Parenthetical citation: According to new research … (Smith, 2020) .
Narrative citation: Smith (2020) notes that …

Multiple authors and corporate authors

The in-text citation changes slightly when a source has multiple authors or an organization as an author. Pay attention to punctuation and the use of the ampersand (&) symbol.

Author type	Parenthetical citation	Narrative citation
One author	(Smith, 2020)	Smith (2020)
Two authors	(Smith & Jones, 2020)	Smith and Jones (2020)
Three or more authors	(Smith et al., 2020)	Smith et al. (2020)
Organization	(Scribbr, 2020)	Scribbr (2020)

When the author, publication date or locator is unknown, take the steps outlined below.

Missing element	What to do	Parenthetical citation
Author	Use the source title.*	( , 2020)
Date	Write “n.d.” for “no date”.	(Smith, n.d.)
Page number	Either use an or omit the page number.	(Smith, 2020, Chapter 3) or (Smith, 2020)

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APA references

APA references generally include information about the author , publication date , title , and source . Depending on the type of source, you may have to include extra information that helps your reader locate the source.

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It is not uncommon for certain information to be unknown or missing, especially with sources found online. In these cases, the reference is slightly adjusted.

Missing element	What to do	Reference format
Author	Start the reference entry with the source title.	Title. (Date). Source.
Date	Write “n.d.” for “no date”.	Author. (n.d.). Title. Source.
Title	Describe the work in square brackets.	Author. (Date). [Description]. Source.

Formatting the APA reference page

On the first line of the page, write the word “References” (in bold and centered). On the second line, start listing your references in alphabetical order .

Apply these formatting guidelines to the APA reference page:

Double spacing (within and between references)
Hanging indent of ½ inch
Legible font (e.g. Times New Roman 12 or Arial 11)
Page number in the top right header

Which sources to include

On the reference page, you only include sources that you have cited in the text (with an in-text citation ). You should not include references to personal communications that your reader can’t access (e.g. emails, phone conversations or private online material).

In addition to the APA Reference Generator, Scribbr provides many more tools and resources that help millions of students and academics every month.

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Educational resources and simple solutions for your research journey

How to Write References in Research Papers: Navigating the Maze (Part 2)

You truly are navigating a maze when it comes to ci tations and the question of how to write references in research pa per s. In part 1 of this article, we touched upon citations, which are pointers embedded in the text of a research paper, to sources of information or to other research relevant to that being described in the research paper. Those pointers lead to references in research papers , which typically appear at the end of the text. Whereas citations merely point us to sources in research papers, references describe those sources in sufficient detail for readers (1) to know the title of each source, who is responsible for its content, and when it was published; (2) to look up those sources; and (3) to obtain the documents in question if required.

Table of Contents

Types of references in research papers

In writing a research paper, a researcher draws upon many sources of information, knowledge, opinions, and so on. One of the the most common type s of reference s in research papers is other research papers published in journals; other common sources include technical reports, handbooks, presentations at conferences, and books. Increasingly, the sources in research papers are digital and include web pages, databases, blog posts, and even tweets and emails.

Not all sources are considered equally credible , and some may not be accessible to all because they are behind paywalls or available only to members of a network (company intranets, for example) or because they are personal exchanges.

How to write references in research papers

If the citations follow the Harvard system, references in a research paper s are sorted alphabetically by the last name of the first author; if the citations follow the Vancouver system, the references are arranged by numbers: the reference corresponding to the first numbered citation is numbered 1, and so on. If a source is cited again, its allocated number does not change.

Some additional conventions govern the alphabetic sorting of references in research papers . For instance, when authors have some papers in which they are the only author and others in which they have one or more co-authors or when the same author or authors have papers published in different years or even within the same year.

Some publishers make even greater demands of references in research papers : authors are expected to sort the list of references alphabetically, as in the Harvard system; then number the sorted list serially; and then renumber all the citations within the text so that each corresponds to its new number!

How to add references in a research paper: Key elements

For a source of information to be described accurately, some minimum details are required. Here’s one example of w rit ing references in research paper s – ‘ Nature 171 : 737’ is a code that, if you know how to decipher it, tells you that it means an article published in Nature (a weekly journal published from the UK) that begins on page 737 of volume 171 of that journal. However, it does not tell you what the article was about, who wrote it, when it was published, or even how long it is. A complete reference in research paper s (Fig. 1), however, tells you that the title of the article was ‘Molecular structure of nucleic acids: a structure for deoxyribose nucleic acid’, that it was written by J. D. Watson and F. H. C. Crick, that it was published in 1953, and that it ran to no more than two pages.

Watson J D and Crick F H C. 1953. Molecular structure of nucleic acids: a structure for deoxyribose nucleic acid. : 737–738

A typical reference to a paper published in a journal

When thinking about how to write research references , remember that the elements that make up a reference to an article published in a journal are different from those that make up a reference to a book (edition if not the first, the publisher, and the place of publication, although the last is no longer considered essential in today’s globalized publishing). The elements that make up a reference to a technical report include the name of the organization issuing that report and the report number, if any, and that to a conference presentation gives the title of the conference, the date(s) on which it was held and the place, the name of the organizer(s) of the conference, and so on.

Note that journals or publishers differ in the elements they expect authors to include when they state how to put references in research papers ; for example, some journals give only minimal information and exclude the titles of articles and some use the ‘elided’ form of page numbers (737–38 instead of 737–738, for example).

Then there is the question of abbreviated names of journals: some publishers abbreviate journal titles and some don’t ( Annals of Applied Biology or Ann. Appl. Biol.). And those who do, often disagree on the correct abbreviation—and on whether the abbreviations should end in dots (whether the word ‘Journal’ should be given as J. or J or Jnl or Jnl.).

Sequence of the elements that make up reference s in research papers

Publishers and journals also differ in the order or sequence in which they present the elements or components of reference s in research papers : usually, British and European publishers put the year of publication after the names of authors whereas US publishers move the year closer to the volume number of the journal.

Even within an element, the sequence of references in research paper s can have subtle differences. In Harvard system, because the last name of the first author is using for sorting, the name is ‘inverted’, that is the last name is given first, followed by initials (Watson J D instead of J D Watson). However, some journals invert the names of all the authors whereas some invert the name of only the first author. In Vancouver system, the names are seldom inverted because the sequence is not alphabetical.

Punctuation to separate the elements that make up references in research papers

The many exasperating details that go into formatting references include punctuation marks (or their absence). In giving the initials of authors, some journals use dots, some journals use space, some use both, and some use neither (Watson J.D. or Watson J D or Watson J. D. or Watson JD). Some use a comma between the last name and the initials whereas some reserve the comma only to separate one name from the next (Watson, J D and Crick, F H C or Watson J D, Crick F H C). Some use ‘and’ some don’t, even when there are only two authors, and some use ‘&’ instead which makes it even more confusing for those struggling with how to write references in a research paper.

When the place of publication was a required element in the case of books, some publishers used the colon and some used the comma (and also changed the order, as in New York: Harper & Row or Harper & Row, New York). Some publishers end each reference with a full stop (period) and some don’t.

Typography of references in research papers

As if the variations mentioned above were not enough, when figuring out how to add references in a research paper , you also have to contend with the differences in typography as well: journal titles in italics or in normal type, volume numbers in bold or in normal type, hyphens or en dashes between page numbers (737-738 or 737–738), and so on.

All is not lost, however, if you despair of ever getting the references in a research paper right. For example, some publishers now insist on correct formatting only after a paper has been accepted for publication. Also, ICMJE, the International Committee of Medical Journal Editors, recommends a set of uniform requirements for manuscripts (the requirements include the formatting of citations and references), and hundreds of medical journals ( www.icmje.org/journals-following-the-icmje-recommendations/ ) have agreed that as long as authors adhere to those recommendations on how to mention references for research papers , any changes to the formatting any journal wants to make will be made by the journal in question.

Lastly, several software packages help authors to automate this mundane task of consistent formatting of references in research paper s—but that is another article and another day.

The details involved in using citations and references correctly can be overwhelming for some of us. While this article covers the key tips to help you understand how to give reference s in research paper s , be sure to check out article 1 of this two-part series for more on what, when and how to cite in a research paper. One way to check whether these are handled correctly in your manuscript is to use Researcher.Life’s AI powered manuscript optimizer , which can flag any discrepancies, departures from standard style, and mismatches between citations and references in research paper s.

R Discovery is a literature search and research reading platform that accelerates your research discovery journey by keeping you updated on the latest, most relevant scholarly content. With 250M+ research articles sourced from trusted aggregators like CrossRef, Unpaywall, PubMed, PubMed Central, Open Alex and top publishing houses like Springer Nature, JAMA, IOP, Taylor & Francis, NEJM, BMJ, Karger, SAGE, Emerald Publishing and more, R Discovery puts a world of research at your fingertips.

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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.

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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Reference List: Basic Rules

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This resourse, revised according to the 7 th edition APA Publication Manual, offers basic guidelines for formatting the reference list at the end of a standard APA research paper. Most sources follow fairly straightforward rules. However, because sources obtained from academic journals carry special weight in research writing, these sources are subject to special rules . Thus, this page presents basic guidelines for citing academic journals separate from its "ordinary" basic guidelines. This distinction is made clear below.

Note: Because the information on this page pertains to virtually all citations, we've highlighted one important difference between APA 6 and APA 7 with an underlined note written in red. For more information, please consult the Publication Manual of the American Psychological Association , (7 th ed.).

Formatting a Reference List

Your reference list should appear at the end of your paper. It provides the information necessary for a reader to locate and retrieve any source you cite in the body of the paper. Each source you cite in the paper must appear in your reference list; likewise, each entry in the reference list must be cited in your text.

Your references should begin on a new page separate from the text of the essay; label this page "References" in bold, centered at the top of the page (do NOT underline or use quotation marks for the title). All text should be double-spaced just like the rest of your essay.

Basic Rules for Most Sources

All lines after the first line of each entry in your reference list should be indented one-half inch from the left margin. This is called hanging indentation.
All authors' names should be inverted (i.e., last names should be provided first).
For example, the reference entry for a source written by Jane Marie Smith would begin with "Smith, J. M."
If a middle name isn't available, just initialize the author's first name: "Smith, J."
Give the last name and first/middle initials for all authors of a particular work up to and including 20 authors ( this is a new rule, as APA 6 only required the first six authors ). Separate each author’s initials from the next author in the list with a comma. Use an ampersand (&) before the last author’s name. If there are 21 or more authors, use an ellipsis (but no ampersand) after the 19th author, and then add the final author’s name.
Reference list entries should be alphabetized by the last name of the first author of each work.
For multiple articles by the same author, or authors listed in the same order, list the entries in chronological order, from earliest to most recent.
Note again that the titles of academic journals are subject to special rules. See section below.
Italicize titles of longer works (e.g., books, edited collections, names of newspapers, and so on).
Do not italicize, underline, or put quotes around the titles of shorter works such as chapters in books or essays in edited collections.

Basic Rules for Articles in Academic Journals

Present journal titles in full.
Italicize journal titles.
For example, you should use PhiloSOPHIA instead of Philosophia, or Past & Present instead of Past and Present.
This distinction is based on the type of source being cited. Academic journal titles have all major words capitalized, while other sources' titles do not.
Capitalize the first word of the titles and subtitles of journal articles , as well as the first word after a colon or a dash in the title, and any proper nouns .
Do not italicize or underline the article title.
Deep blue: The mysteries of the Marianas Trench.
Oceanographic Study: A Peer-Reviewed Publication

Please note: While the APA manual provides examples of how to cite common types of sources, it does not cover all conceivable sources. If you must cite a source that APA does not address, the APA suggests finding an example that is similar to your source and using that format. For more information, see page 282 of the Publication Manual of the American Psychological Association , 7 th ed.

Journal Article References

This page contains reference examples for journal articles, including the following:

Journal article
Journal article with an article number
Journal article with missing information
Retracted journal article
Retraction notice for a journal article
Abstract of a journal article from an abstract indexing database
Monograph as part of a journal issue
Online-only supplemental material to a journal article

1. Journal article

Grady, J. S., Her, M., Moreno, G., Perez, C., & Yelinek, J. (2019). Emotions in storybooks: A comparison of storybooks that represent ethnic and racial groups in the United States. Psychology of Popular Media Culture , 8 (3), 207–217. https://doi.org/10.1037/ppm0000185

Parenthetical citation : (Grady et al., 2019)
Narrative citation : Grady et al. (2019)
If a journal article has a DOI, include the DOI in the reference.
Always include the issue number for a journal article.
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 works of limited circulation or original, proprietary content, such as UpToDate .
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.

2. Journal article with an article number

Jerrentrup, A., Mueller, T., Glowalla, U., Herder, M., Henrichs, N., Neubauer, A., & Schaefer, J. R. (2018). Teaching medicine with the help of “Dr. House.” PLoS ONE , 13 (3), Article e0193972. https://doi.org/10.1371/journal.pone.0193972

Parenthetical citation : (Jerrentrup et al., 2018)
Narrative citation : Jerrentrup et al. (2018)
If the journal article has an article number instead of a page range, include the word “Article” and then the article number instead of the page range.

3. Journal article with missing information

Missing volume number.

Lipscomb, A. Y. (2021, Winter). Addressing trauma in the college essay writing process. The Journal of College Admission , (249), 30–33. https://www.catholiccollegesonline.org/pdf/national_ccaa_in_the_news_-_nacac_journal_of_college_admission_winter_2021.pdf

Missing issue number

Sanchiz, M., Chevalier, A., & Amadieu, F. (2017). How do older and young adults start searching for information? Impact of age, domain knowledge and problem complexity on the different steps of information searching. Computers in Human Behavior , 72 , 67–78. https://doi.org/10.1016/j.chb.2017.02.038

Missing page or article number

Butler, J. (2017). Where access meets multimodality: The case of ASL music videos. Kairos: A Journal of Rhetoric, Technology, and Pedagogy , 21 (1). http://technorhetoric.net/21.1/topoi/butler/index.html

Parenthetical citations : (Butler, 2017; Lipscomb, 2021; Sanchiz et al., 2017)
Narrative citations : Butler (2017), Lipscomb (2021), and Sanchiz et al. (2017)
If the journal does not use volume, issue, and/or article or page numbers, omit the missing element(s) from the reference.
If the journal is published quarterly and the month or season (Fall, Winter, Spring, Summer) is noted, include that with the date element; see the Lipscomb example.
If the volume, issue, and/or article or page numbers have simply not yet been assigned, use the format for an advance online publication (see Example 7 in the Publication Manual ) or an in-press article (see Example 8 in the Publication Manual ).

4. Retracted journal article

Joly, J. F., Stapel, D. A., & Lindenberg, S. M. (2008). Silence and table manners: When environments activate norms. Personality and Social Psychology Bulletin , 34 (8), 1047–1056. https://doi.org/10.1177/0146167208318401 (Retraction published 2012, Personality and Social Psychology Bulletin, 38 [10], 1378)

Parenthetical citation : (Joly et al., 2008)
Narrative citation : Joly et al. (2008)
Use this format to cite the retracted article itself, for example, to discuss the contents of the retracted article.
First provide publication details of the original article. Then provide information about the retraction in parentheses, including its year, journal, volume, issue, and page number(s).

5. Retraction notice for a journal article

de la Fuente, R., Bernad, A., Garcia-Castro, J., Martin, M. C., & Cigudosa, J. C. (2010). Retraction: Spontaneous human adult stem cell transformation. Cancer Research , 70 (16), 6682. https://doi.org/10.1158/0008-5472.CAN-10-2451

The Editors of the Lancet. (2010). Retraction—Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet , 375 (9713), 445. https://doi.org/10.1016/S0140-6736(10)60175-4

Parenthetical citations : (de la Fuente et al., 2010; The Editors of the Lancet, 2010)
Narrative citations : de la Fuente et al. (2010) and The Editors of the Lancet (2010)
Use this format to cite a retraction notice rather than a retracted article, for example, to provide information on why an article was retracted.
The author of the retraction notice may be an editor, editorial board, or some or all authors of the article. Examine the retraction notice to determine who to credit as the author.
Reproduce the title of the retraction notice as shown on the work. Note that the title may include the words “retraction,” “retraction notice,” or “retraction note” as well as the title of the original article.

6. Abstract of a journal article from an abstract indexing database

Hare, L. R., & O'Neill, K. (2000). Effectiveness and efficiency in small academic peer groups: A case study (Accession No. 200010185) [Abstract from Sociological Abstracts]. Small Group Research , 31 (1), 24–53. https://doi.org/10.1177/104649640003100102

Parenthetical citation : (Hare & O’Neill, 2000)
Narrative citation : Hare and O’Neill (2000)
Although it is preferable to cite the whole article, the abstract can be cited if that is your only available source.
The foundation of the reference is the same as for a journal article.
If the abstract has a database accession number, place it in parentheses after the title.
Note that you retrieved only the abstract by putting the words “Abstract from” and then the name of the abstract indexing database in square brackets. Place this bracketed description after the title and any accession number.
Accession numbers are sometimes referred to as unique identifiers or as publication numbers (e.g., as PubMed IDs); use the term provided by the database in your reference.

7. Monograph as part of a journal issue

Ganster, D. C., Schaubroeck, J., Sime, W. E., & Mayes, B. T. (1991). The nomological validity of the Type A personality among employed adults [Monograph]. Journal of Applied Psychology , 76 (1), 143–168. http://doi.org/10.1037/0021-9010.76.1.143

Parenthetical citation : (Ganster et al., 1991)
Narrative citation : Ganster et al. (1991)
For a monograph with an issue (or whole) number, include the issue number in parentheses followed by the serial number, for example, 58 (1, Serial No. 231).
For a monograph bound separately as a supplement to a journal, give the issue number and supplement or part number in parentheses after the volume number, for example, 80 (3, Pt. 2).

8. Online-only supplemental material to a journal article

Freeberg, T. M. (2019). From simple rules of individual proximity, complex and coordinated collective movement [Supplemental material]. Journal of Comparative Psychology , 133 (2), 141–142. https://doi.org/10.1037/com0000181

Parenthetical citation : (Freeberg, 2019)
Narrative citation : Freeberg (2019)
Include the description “[Supplemental material]” in square brackets after the article title.
If you cite both the main article and the supplemental material, provide only a reference for the article.

Journal article references are covered in the seventh edition APA Style manuals in the Publication Manual Section 10.1 and the Concise Guide Section 10.1

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Manchester Metropolitan University (MMU)
University of the West of England (UWE)

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References: Common Reference List Examples

Article (with doi).

Alvarez. E., & Tippins, S. (2019). Socialization agents that Puerto Rican college students use to make financial decisions. Journal of Social Change , 11 (1), 75–85. https://doi.org/10.5590/JOSC.2019.11.1.07

Laplante, J. P., & Nolin, C. (2014). Consultas and socially responsible investing in Guatemala: A case study examining Maya perspectives on the Indigenous right to free, prior, and informed consent. Society & Natural Resources , 27 , 231–248. https://doi.org/10.1080/08941920.2013.861554

Provide a DOI number if there is one. DOI stands for "digital object identifier," a number specific to the article that can help others locate the source. Use CrossRef.org to locate DOI information. This rule applies regardless of how the source was accessed (e.g., online, paper, etc.; see APA 7, Section 9.34).

In APA 7, format the DOI as a web address. Active hyperlinks for DOIs and URLs should be used for documents meant for screen reading. Present these hyperlinks in blue and underlined text (the default formatting in Microsoft Word), although plain black text is also acceptable. Be consistent in the formatting choice for DOIs and URLs throughout the reference list. (Note that this guidance has changed from APA 6 where all hyperlink formatting was removed and no active links were included. In APA 6, the URLs appeared in plain, black type and did not link out from the document.)

Also see our Quick Answer FAQ, "Can I use the DOI format provided by library databases?"

For journal articles that are assigned article numbers rather than page ranges, include the article number in place of the page range.

For more on citing electronic resources, see Electronic Sources References .

Article (Without DOI)

Found in a common academic research database or in print.

Casler , T. (2020). Improving the graduate nursing experience through support on a social media platform. MEDSURG Nursing , 29 (2), 83–87.

If an article does not have a DOI and you retrieved it from a common academic research database through the university library, there is no need to include any additional electronic retrieval information. The reference list entry looks like the entry for a print copy of the article. (This format differs from APA 6 guidelines that recommended including the URL of a journal's homepage when the DOI was not available.)

Note that APA 7 has additional guidance on reference list entries for articles found only in specific databases or archives such as Cochrane Database of Systematic Reviews, UpToDate, ProQuest Dissertations and Theses Global, and university archives. See APA 7, Section 9.30 for more information.

Found on an Open Access Website

Eaton, T. V., & Akers, M. D. (2007). Whistleblowing and good governance. CPA Journal , 77 (6), 66–71. http://archives.cpajournal.com/2007/607/essentials/p58.htm

Provide the direct web address/URL to a journal article found on the open web, often on an open access journal's website.

In APA 7, active hyperlinks for DOIs and URLs should be used for documents meant for screen reading. Present these hyperlinks in blue and underlined text (the default formatting in Microsoft Word), although plain black text is also acceptable. Be consistent in your formatting choice for DOIs and URLs throughout your reference list. (Note that this guidance has changed from APA 6 where all hyperlink formatting was removed and no active links were included. In APA 6, the URLs appeared in plain, black type and did not link out from the document.)

Weinstein, J. A. (2010). Social change (3rd ed.). Rowman & Littlefield.

If the book has an edition number, include it in parentheses after the title of the book. If the book does not list any edition information, do not include an edition number. The edition number is not italicized. (Note: In APA 6, the location of the publisher was included. This is no longer the case in APA 7; only the publisher name is provided.) Regarding publisher name, when a publisher is named after a person (as is the case with Lawrence Erlbaum or John Wiley), list only the surname (Erlbaum or Wiley). In addition, exclude “Publishers,” “Inc.,” and “Co.” from publisher names in reference entries.

American Nurses Association. (2010). Nursing: Scope and standards of practice (2nd ed.).

In APA 7, if the author and publisher are the same, only include the author in its regular place and omit the publisher. (Note that this is a change from APA 6, where the term “Author” was used for the publisher instead of repeating the name.)

Lencioni, P. (2012). The advantage: Why organizational health trumps everything else in business . Jossey-Bass. https://amzn.to/343XPSJ

As a change from APA 6 to APA 7, it is no longer necessary to include the ebook format in the title. However, if you listened to an audiobook and the content differs from the text version (e.g., abridged content) or your discussion highlights elements of the audiobook (e.g., narrator's performance), then note that it is an audiobook in the title element in brackets. For ebooks and online audiobooks, also include the DOI number (if available) or nondatabase URL but leave out the electronic retrieval element if the ebook was found in a common academic research database, as with journal articles. APA 7 allows for the shortening of long DOIs and URLs, as shown in this example. See APA 7, Section 9.36 for more information.

Chapter in an Edited Book

Poe, M. (2017). Reframing race in teaching writing across the curriculum. In F. Condon & V. A. Young (Eds.), Performing antiracist pedagogy in rhetoric, writing, and communication (pp. 87–105). University Press of Colorado.

Include the page numbers of the chapter in parentheses after the book title. The page range should not be italicized.

Christensen, L. (2001). For my people: Celebrating community through poetry. In B. Bigelow, B. Harvey, S. Karp, & L. Miller (Eds.), Rethinking our classrooms: Teaching for equity and justice (Vol. 2, pp. 16–17). Rethinking Schools.

Also include volume number and edition numbers in the parenthetical information after the book title where relevant.

Freud, S. (1961). The ego and the id. In J. Strachey (Ed.), The standard edition of the complete psychological works of Sigmund Freud (Vol. 19, pp. 3-66). Hogarth Press. (Original work published 1923)

When a text has been republished as part of an anthology collection, after the author’s name include the date of the version that was read. At the end of the entry, place the date of the original publication inside parenthesis along with the note “original work published.” For in-text citations of republished work, use both dates in the parenthetical citation, original date first with a slash separating the years, as in this example: Freud (1923/1961). For more information on reprinted or republished works, see APA 7, Sections 9.40-9.41.

Dissertations or Theses

Retrieved from a database

Nalumango, K. (2019). Perceptions about the asylum-seeking process in the United States after 9/11 (Publication No. 13879844) [Doctoral dissertation, Walden University]. ProQuest Dissertations and Theses.

Retrieved From an Institutional or Personal Website

Evener. J. (2018). Organizational learning in libraries at for-profit colleges and universities [Doctoral dissertation, Walden University]. ScholarWorks. https://scholarworks.waldenu.edu/cgi/viewcontent.cgi?article=6606&context=dissertations

Unpublished Dissertation or Thesis

Kirwan, J. G. (2005). An experimental study of the effects of small-group, face-to-face facilitated dialogues on the development of self-actualization levels: A movement towards fully functional persons [Unpublished doctoral dissertation]. Saybrook Graduate School and Research Center.

For further examples and information, see APA 7, Section 10.6.

Legal Material

For legal references, APA follows the recommendations of The Bluebook: A Uniform System of Citation , so if you have any questions beyond the examples provided in APA, seek out that resource as well.

Court Decisions

Reference format:

Name v. Name, Volume Reporter Page (Court Date). URL

Sample reference entry:

Brown v. Board of Education, 347 U.S. 483 (1954). https://www.oyez.org/cases/1940-1955/347us483

Sample citation:

In Brown v. Board of Education (1954), the Supreme Court ruled racial segregation in schools unconstitutional.

Note: Italicize the case name when it appears in the text of your paper rather than citing it—for example, “Cases such as Brown v. Board of Education and Parents Involved in Community Schools v. Seattle illustrate ...”

Name of Act, Title Source § Section Number (Year). URL

Sample reference entry for a federal statute:

Individuals With Disabilities Education Act, 20 U.S.C. § 1400 et seq. (2004). https://www.congress.gov/108/plaws/publ446/PLAW-108publ446.pdf

Sample reference entry for a state statute:

Minnesota Nurse Practice Act, Minn. Stat. §§ 148.171 et seq. (2019). https://www.revisor.mn.gov/statutes/cite/148.171

Sample citation: Minnesota nurses must maintain current registration in order to practice (Minnesota Nurse Practice Act, 2010).

Note: The § symbol stands for "section." Use §§ for sections (plural). To find this symbol in Microsoft Word, go to "Insert" and click on Symbol." Look in the Latin 1-Supplement subset.

Note: U.S.C. stands for "United States Code."

Note: The Latin abbreviation " et seq. " means "and what follows" and is used when the act includes the cited section and ones that follow.

Note: List the chapter first followed by the section or range of sections.

Unenacted Bills and Resolutions

(Those that did not pass and become law)

Title [if there is one], bill or resolution number, xxx Cong. (year). URL

Sample reference entry for Senate bill:

Anti-Phishing Act, S. 472, 109th Cong. (2005). https://www.congress.gov/bill/109th-congress/senate-bill/472

Sample reference entry for House of Representatives resolution:

Anti-Phishing Act, H.R. 1099, 109th Cong. (2005). https://www.congress.gov/bill/109th-congress/house-bill/1099

The Anti-Phishing Act (2005) proposed up to 5 years prison time for people running Internet scams.

These are the three legal areas you may be most apt to cite in your scholarly work. For more examples and explanation, see APA 7, Chapter 11.

Magazine Article

Clay, R. (2008, June). Science vs. ideology: Psychologists fight back about the misuse of research. Monitor on Psychology , 39 (6). https://www.apa.org/monitor/2008/06/ideology

Note that for citations, include only the year: Clay (2008). For magazine articles retrieved from a common academic research database, leave out the URL. For magazine articles from an online news website that is not an online version of a print magazine, follow the format for a webpage reference list entry.

Newspaper Article

Baker, A. (2014, May 7). Connecticut students show gains in national tests. New York Times . http://www.nytimes.com/2014/05/08/nyregion/national-assessment-of-educational-progress-results-in-Connecticut-and-New-Jersey.html

Include the full date in the format Year, Month Day. Do not include a retrieval date for periodical sources found on websites. Note that for citations, include only the year: Baker (2014). For newspaper articles retrieved from a common academic research database, leave out the URL. For newspaper articles from an online news website that is not an online version of a print newspaper, follow the format for a webpage reference list entry.

Technical and Research Reports

The general structure for a technical or research report is as follows:

Author, A. A. (Publication Year). Title of work . Publisher Name. DOI or URL

Edwards, C. (2015). Lighting levels for isolated intersections: Leading to safety improvements (Report No. MnDOT 2015-05). Center for Transportation Studies. http://www.cts.umn.edu/Publications/ResearchReports/reportdetail.html?id=2402

Technical and research reports by governmental agencies and other research institutions usually follow a different publication process than scholarly, peer-reviewed journals. However, they present original research and are often useful for research papers. Sometimes, researchers refer to these types of reports as gray literature , and white papers are a type of this literature. See APA 7, Section 10.4 for more information.

American Federation of Teachers. (n.d.). Community schools . http://www.aft.org/issues/schoolreform/commschools/index.cfm

If there is no specified author, then use the organization’s name as the author. In such a case, there is no need to repeat the organization's name after the title.

Vartan, S. (2018, January 30). Why vacations matter for your health . CNN. https://www.cnn.com/travel/article/why-vacations-matter/index.html

For webpages from news websites, include the site name after the title and before the URL. If the source is an online newspaper or magazine, follow the models in the previous sections of this page. In APA 7, active hyperlinks for DOIs and URLs should be used for documents meant for screen reading. Present these hyperlinks in blue and underlined text (the default formatting in Microsoft Word), although plain black text is also acceptable. Be consistent in your formatting choice for DOIs and URLs throughout your reference list. (Note that this guidance has changed from APA 6 where all hyperlink formatting was removed, and no active links were included. In APA 6, the URLs appeared in plain, black type and did not link out from the document.)

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Referencing Generator

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What Is Cite This For Me’s Reference Generator?

Cite This For Me’s open-access generator is an automated citation machine that turns any of your sources into references in just a click. Using a reference generator helps students to integrate referencing into their research and writing routine; turning a time-consuming ordeal into a simple task.

A referencing generator accesses information from across the web, drawing the relevant information into a fully-formatted bibliography that clearly presents all of the sources that have contributed to your work.

If you don’t know how to reference a website correctly, or have a fast-approaching deadline, Cite This For Me’s accurate and intuitive reference generator will lend you the confidence to realise your full academic potential. In order to get a grade that reflects all your hard work, your references must be accurate and complete. Using a citation machine not only saves you time but also ensures that you don’t lose valuable marks on your assignment.

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Why Do I Need To Reference?

Simply put, when another source contributes to your work, you have to give the original owner the appropriate credit. After all, you wouldn’t steal someone else’s possessions so why would you steal their ideas?

Regardless of whether you are referencing a website, an article or a podcast, any factual material or ideas you take from another source must be acknowledged in a citation unless it is common knowledge (e.g. Winston Churchill was English). Failing to credit all of your sources, even when you’ve paraphrased or completely reworded the information, is plagiarism. Plagiarising will result in disciplinary action, which can range from losing precious marks on your assignment to expulsion from your university.

What’s more, attributing your research infuses credibility and authority into your work, both by supporting your own ideas and by demonstrating the breadth of your research. For many students, crediting sources can be a confusing and tedious process, but it’s a surefire way to improve the quality of your work so it’s essential to get it right. Luckily for you, using Cite This For Me’s reference generator makes creating accurate references easier than ever, leaving more time for you to excel in your studies.

In summary, the citing process serves three main functions:

To validate the statements and conclusions in your work by providing directions to other sound sources that support and verify them.
To help your readers locate, read and check your sources, as well as establishing their contribution to your work.
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Published: 02 September 2024

Green spaces provide substantial but unequal urban cooling globally

Yuxiang Li 1 ,
Jens-Christian Svenning ORCID: orcid.org/0000-0002-3415-0862 2 ,
Weiqi Zhou ORCID: orcid.org/0000-0001-7323-4906 3 , 4 , 5 ,
Kai Zhu ORCID: orcid.org/0000-0003-1587-3317 6 ,
Jesse F. Abrams ORCID: orcid.org/0000-0003-0411-8519 7 ,
Timothy M. Lenton ORCID: orcid.org/0000-0002-6725-7498 7 ,
William J. Ripple 8 ,
Zhaowu Yu ORCID: orcid.org/0000-0003-4576-4541 9 ,
Shuqing N. Teng 1 ,
Robert R. Dunn 10 &
Chi Xu ORCID: orcid.org/0000-0002-1841-9032 1

Nature Communications volume 15 , Article number: 7108 ( 2024 ) Cite this article

Metrics details

Climate-change mitigation
Urban ecology

Climate warming disproportionately impacts countries in the Global South by increasing extreme heat exposure. However, geographic disparities in adaptation capacity are unclear. Here, we assess global inequality in green spaces, which urban residents critically rely on to mitigate outdoor heat stress. We use remote sensing data to quantify daytime cooling by urban greenery in the warm seasons across the ~500 largest cities globally. We show a striking contrast, with Global South cities having ~70% of the cooling capacity of cities in the Global North (2.5 ± 1.0 °C vs. 3.6 ± 1.7 °C). A similar gap occurs for the cooling adaptation benefits received by an average resident in these cities (2.2 ± 0.9 °C vs. 3.4 ± 1.7 °C). This cooling adaptation inequality is due to discrepancies in green space quantity and quality between cities in the Global North and South, shaped by socioeconomic and natural factors. Our analyses further suggest a vast potential for enhancing cooling adaptation while reducing global inequality.

Introduction

Heat extremes are projected to be substantially intensified by global warming 1 , 2 , imposing a major threat to human mortality and morbidity in the coming decades 3 , 4 , 5 , 6 . This threat is particularly concerning as a majority of people now live in cities 7 , including those cities suffering some of the hottest climate extremes. Cities face two forms of warming: warming due to climate change and warming due to the urban heat island effect 8 , 9 , 10 . These two forms of warming have the potential to be additive, or even multiplicative. Climate change in itself is projected to result in rising maximum temperatures above 50 °C for a considerable fraction of the world if 2 °C global warming is exceeded 2 ; the urban heat island effect will cause up to >10 °C additional (surface) warming 11 . Exposures to temperatures above 35 °C with high humidity or above 40 °C with low humidity can lead to lethal heat stress for humans 12 . Even before such lethal temperatures are reached, worker productivity 13 and general health and well-being 14 can suffer. Heat extremes are especially risky for people living in the Global South 15 , 16 due to warmer climates at low latitudes. Climate models project that the lethal temperature thresholds will be exceeded with increasing frequencies and durations, and such extreme conditions will be concentrated in low-latitude regions 17 , 18 , 19 . These low-latitude regions overlap with the major parts of the Global South where population densities are already high and where population growth rates are also high. Consequently, the number of people exposed to extreme heat will likely increase even further, all things being equal 16 , 20 . That population growth will be accompanied by expanded urbanization and intensified urban heat island effects 21 , 22 , potentially exacerbating future Global North-Global South heat stress exposure inequalities.

Fortunately, we know that heat stress can be buffered, in part, by urban vegetation 23 . Urban green spaces, and especially urban forests, have proven an effective means through which to ameliorate heat stress through shading 24 , 25 and transpirational cooling 26 , 27 . The buffering effect of urban green spaces is influenced by their area (relative to the area of the city) and their spatial configuration 28 . In this context, green spaces become a kind of infrastructure that can and should be actively managed. At broad spatial scales, the effect of this urban green infrastructure is also mediated by differences among regions, whether in their background climate 29 , composition of green spaces 30 , or other factors 31 , 32 , 33 , 34 . The geographic patterns of the buffering effects of green spaces, whether due to geographic patterns in their areal extent or region-specific effects, have so far been poorly characterized.

On their own, the effects of climate change and urban heat islands on human health are likely to become severe. However, these effects will become even worse if they fall disproportionately in cities or countries with less economic ability to invest in green space 35 or in other forms of cooling 36 , 37 . A number of studies have now documented the so-called ‘luxury effect,’ wherein lower-income parts of cities tend to have less green space and, as a result, reduced biodiversity 38 , 39 . Where the luxury effect exists, green space and its benefits become, in essence, a luxury good 40 . If the luxury effect holds among cities, and lower-income cities also have smaller green spaces, the Global South may have the least potential to mitigate the combined effects of climate warming and urban heat islands, leading to exacerbated and rising inequalities in heat exposure 41 .

Here, we assess the global inequalities in the cooling capability of existing urban green infrastructure across urban areas worldwide. To this end, we use remotely sensed data to quantify three key variables, i.e., (1) cooling efficiency, (2) cooling capacity, and (3) cooling benefit of existing urban green infrastructure for ~500 major cities across the world. Urban green infrastructure and temperature are generally negatively and relatively linearly correlated at landscape scales, i.e., higher quantities of urban green infrastructure yield lower temperatures 42 , 43 . Cooling efficiency is widely used as a measure of the extent to which a given proportional increase in the area of urban green infrastructure leads to a decrease in temperature, i.e., the slope of the urban green infrastructure-temperature relationship 42 , 44 , 45 (see Methods for details). This simple metric allows quantifying the quality of urban green infrastructure in terms of ameliorating the urban heat island effect. Meanwhile, the extent to which existing urban green infrastructure cools down an entire city’s surface temperatures (compared to the non-vegetated built-up areas) is referred to as cooling capacity. Hence, cooling capacity is a function of the total quantity of urban green infrastructure and its cooling efficiency (see Methods).

As a third step, we account for the spatial distributions of urban green infrastructure and populations to quantify the benefit of cooling mitigation received by an average urban inhabitant in each city given their location. This cooling benefit is a more direct measure of the cooling realized by people, after accounting for the within-city geography of urban green infrastructure and population density. We focus on cooling capacity and cooling benefit as the measures of the cooling capability of individual cities for assessing their global inequalities. We are particularly interested in linking cooling adaptation inequality with income inequality 40 , 46 . While this can be achieved using existing income metrics for country classifications 47 , here we use the traditional Global North/South classification due to its historical ties to geography which is influential in climate research.

Results and discussion

Our analyses indicate that existing green infrastructure of an average city has a capability of cooling down surface temperatures by ~3 °C during warm seasons. However, a concerning disparity is evident; on average Global South cities have only two-thirds the cooling capacity and cooling benefit compared to Global North cities. This inequality is attributable to the differences in both quantity and quality of existing urban green infrastructure among cities. Importantly, we find that there exists considerable potential for many cities to enhance the cooling capability of their green infrastructure; achieving this potential could dramatically reduce global inequalities in adaptation to outdoor heat stress.

Quantifying cooling inequality

Our analyses showed that both the quantity and quality of the existing urban green infrastructure vary greatly among the world’s ~500 most populated cities (see Methods for details, and Fig. 1 for examples). The quantity of urban green infrastructure measured based on remotely sensed indicators of spectral greenness (Normalized Difference Vegetation Index, NDVI, see Methods) had a coefficient of variation (CV) of 35%. Similarly, the quality of urban green infrastructure in terms of cooling efficiency (daytime land surface temperatures during peak summer) had a CV of 37% (Supplementary Figs. 1 , 2 ). The global mean value of cooling capacity is 2.9 °C; existing urban green infrastructure ameliorates warm-season heat stress by 2.9 °C of surface temperature in an average city. In truth, however, the variation in cooling capacity was great (global CV in cooling capacity as large as ~50%), such that few cities were average. This variation is strongly geographically structured. Cities closer to the equator - tropical and subtropical cities - tend to have relatively weak cooling capacities (Fig. 2a, b ). As Global South countries are predominantly located at low latitudes, this pattern leads to a situation in which Global South cities, which tend to be hotter and relatively lower-income, have, on average, approximately two-thirds the cooling capacity of the Global North cities (2.5 ± 1.0 vs. 3.6 ± 1.7°C, Wilcoxon test, p = 2.7e-12; Fig. 2c ). The cities that most need to rely on green infrastructure are, at present, those that are least able to do so.

a , e , i , m , q Los Angeles, US. b , f , j , n , r Paris, France. c , g , k , o , s Shanghai, China. d , h , l , p , t Cairo, Egypt. Local cooling efficiency is calculated for different local climate zone types to account for within-city heterogeneity. In densely populated parts of cities, local cooling capacity tends to be lower due to reduced green space area, whereas local cooling benefit (local cooling capacity multiplied by a weight term of local population density relative to city mean) tends to be higher as more urban residents can receive cooling amelioration.

a Global distribution of cooling capacity for the 468 major urbanized areas. b Latitudinal pattern of cooling capacity. c Cooling capacity difference between the Global North and South cities. The cooling capacity offered by urban green infrastructure evinces a latitudinal pattern wherein lower-latitude cities have weaker cooling capacity ( b , cubic-spline fitting of cooling capacity with 95% confidence interval is shown), representing a significant inequality between Global North and South countries: city-level cooling capacity for Global North cities are about 1.5-fold higher than in Global South cities ( c ). Data are presented as box plots, where median values (center black lines), 25th percentiles (box lower bounds), 75th percentiles (box upper bounds), whiskers extending to 1.5-fold of the interquartile range (IQR), and outliers are shown. The tails of the cooling capacity distributions are truncated at zero as all cities have positive values of cooling capacity. Notice that no cities in the Global South have a cooling capacity greater than 5.5 °C ( c ). This is because no cities in the Global South have proportional green space areas as great as those seen in the Global North (see also Fig. 4b ). A similar pattern is found for cooling benefit (Supplementary Fig. 3 ). The two-sided non-parametric Wilcoxon test was used for statistical comparisons.

When we account for the locations of urban green infrastructure relative to humans within cities, the cooling benefit of urban green infrastructure realized by an average urban resident generally becomes slightly lower than suggested by cooling capacity (see Methods; Supplementary Fig. 3 ). Urban residents tend to be densest in the parts of cities with less green infrastructure. As a result, the average urban resident experiences less cooling amelioration than expected. However, this heterogeneity has only a minor effect on global-scale inequality. As a result, the geographic trends in cooling capacity and cooling benefit are similar: mean cooling benefit for an average urban resident also presents a 1.5-fold gap between Global South and North cities (2.2 ± 0.9 vs. 3.4 ± 1.7 °C, Wilcoxon test, p = 3.2e-13; Supplementary Fig. 3c ). Urban green infrastructure is a public good that has the potential to help even the most marginalized populations stay cool; unfortunately, this public benefit is least available in the Global South. When walking outdoors, the average person in an average Global South city receives only two-thirds the cooling amelioration from urban green infrastructure experienced by a person in an average Global North city. The high cooling amelioration capacity and benefit of the Global North cities is heavily influenced by North America (specifically, Canada and the US), which have both the highest cooling efficiency and the largest area of green infrastructure, followed by Europe (Supplementary Fig. 4 ).

One way to illustrate the global inequality of cooling capacity or benefit is to separately look at the cities that are most and least effective in ameliorating outdoor heat stress. Our results showed that ~85% of the 50 most effective cities (with highest cooling capacity or cooling benefit) are located in the Global North, while ~80% of the 50 least effective are Global South cities (Fig. 3 , Supplementary Fig. 5 ). This is true without taking into account the differences in the background temperatures and climate warming of these cities, which will exacerbate the effects on human health; cities in the Global South are likely to be closer to the limits of human thermal comfort and even, increasingly, the limits of the temperatures and humidities (wet-bulb temperatures) at which humans can safely work or even walk, such that the ineffectiveness of green spaces in those cities in cooling will lead to greater negative effects on human health 48 , work 14 , and gross domestic product (GDP) 49 . In addition, Global South cities commonly have higher population densities (Fig. 3 , Supplementary Fig. 5 ) and are projected to have faster population growth 50 . This situation will plausibly intensify the urban heat island effect because of the need of those populations for housing (and hence tensions between the need for buildings and the need for green spaces). It will also increase the number of people exposed to extreme urban heat island effects. Therefore, it is critical to increase cooling benefit via expanding urban green spaces, so that more people can receive the cooling mitigation from a given new neighboring green space if they live closer to each other. Doing so will require policies that incentivize urban green spaces as well as architectural innovations that make innovations such as plant-covered buildings easier and cheaper to implement.

The axes on the right are an order of magnitude greater than those on the left, such that the cooling capacity of Charlotte in the United States is about 37-fold greater than that of Mogadishu (Somalia) and 29-fold greater than that of Sana’a (Yemen). The cities presenting lowest cooling capacities are most associated with Global South cities at higher population densities.

Of course, cities differ even within the Global North or within the Global South. For example, some Global South cities have high green space areas (or relatively high cooling efficiency in combination with moderate green space areas) and hence high cooling capacity. These cities, such as Pune (India), will be important to study in more detail, to shed light on the mechanistic details of their cooling abilities as well as the sociopolitical and other factors that facilitated their high green area coverage and cooling capabilities (Supplementary Figs. 6 , 7 ).

We conducted our primary analyses using a spatial grain of 100-m grid cells and Landsat NDVI data for quantifying spectral greenness. Our results, however, were robust at the coarser spatial grain of 1 km. We find a slightly larger global cooling inequality (~2-fold gap between Global South and North cities) at the 1-km grain using MODIS data (see Methods and Supplementary Fig. 17 ). MODIS data have been frequently used for quantifying urban heat island effects and cooling mitigation 44 , 45 , 51 . Our results reinforce its robustness for comparing urban thermal environments between cities across broad scales.

Influencing factors

The global inequality of cooling amelioration could have a number of proximate causes. To understand their relative influence, we first separately examined the effects of quality (cooling efficiency) and quantity (NDVI as a proxy indicator of urban green space area) of urban green infrastructure. The simplest null model is one in which cooling capacity (at the city scale) and cooling benefit (at the human scale) are driven primarily by the proportional area in a city dedicated to green spaces. Indeed, we found that both cooling capacity and cooling benefit were strongly correlated with urban green space area (Fig. 4 , Supplementary Fig. 8 ). This finding is useful with regards to practical interventions. In general, cities that invest in saving or restoring more green spaces will receive more cooling benefits from those green spaces. By contrast, differences among cities in cooling efficiency played a more minor role in determining the cooling capacity and benefit of cities (Fig. 4 , Supplementary Fig. 8 ).

a Relationship between cooling efficiency and cooling capacity. b Relationship between green space area (measured by mean Landsat NDVI in the hottest month of 2018) and cooling capacity. Note that the highest level of urban green space area in the Global South cities is much lower than that in the Global North (dashed line in b ). Gray bands indicate 95% confidence intervals. Two-sided t-tests were conducted. c A piecewise structural equation model based on assumed direct and indirect (through influencing cooling efficiency and urban green space area) effects of essential natural and socioeconomic factors on cooling capacity. Mean annual temperature and precipitation, and topographic variation (elevation range) are selected to represent basic background natural conditions; GDP per capita is selected to represent basic socioeconomic conditions. The spatial extent of built-up areas is included to correct for city size. A bi-directional relationship (correlation) is fitted between mean annual temperature and precipitation. Red and blue solid arrows indicate significantly negative and positive coefficients with p ≤ 0.05, respectively. Gray dashed arrows indicate p > 0.05. The arrow width illustrates the effect size. Similar relationships are found for cooling benefits realized by an average urban resident (see Supplementary Fig. 8 ).

A further question is what shapes the quality and quantity of urban green infrastructure (which in turn are driving cooling capacity)? Many inter-correlated factors are possibly operating at multiple scales, making it difficult to disentangle their effects, especially since experiment-based causal inference is usually not feasible for large-scale urban systems. From a macroscopic perspective, we test the simple hypothesis that the background natural and socioeconomic conditions of cities jointly affect their cooling capacity and benefit in both direct and indirect ways. To this end, we constructed a minimal structural equation model including only the most essential variables reflecting background climate (mean annual temperature and precipitation), topographic variation (elevation range), as well as gross domestic product (GDP) per capita and city area (see Methods; Fig. 4c ).

We found that the quantity of green spaces in a city (again, in proportion to its size) was positively correlated with GDP per capita and city area; wealthier cities have more green spaces. It is well known that wealth and green spaces are positively correlated within cities (the luxury effect) 40 , 46 ; our analysis shows that a similar luxury effect occurs among them at a global scale. In addition, larger cities often have proportionally more green spaces, an effect that may be due to the tendency for large cities (particularly in the US and Canada) to have lower population densities. Cities that were hotter and had more topographic variation tended to have fewer green spaces and those that were more humid tended to have more green spaces. Given that temperature and humidity are highly correlated with the geography of the Global South and Global North, it is difficult to know whether these effects are due to the direct effects of temperature and precipitation, for example, on the growth rate of vegetation and hence the transition of abandoned lots into green spaces, or are associated with historical, cultural and political differences that via various mechanisms correlate to climate. Our structural equation model explained only a small fraction of variation among cities in their cooling efficiency, which is to say the quality of their green space. Cooling efficiency was modestly influenced by background temperature and precipitation—the warmer a city, the greater the cooling efficiency in that city; conversely, the more humid a city the less the cooling efficiency of that city.

Our analyses suggested that the lower cooling adaptation capabilities of Global South cities can be explained by their lower quantity of green infrastructure and, to a much lesser extent, their weaker cooling efficiency (quality; Supplementary Fig. 2 ). These patterns appear to be in part structured by GDP, but are also associated with climatic conditions 39 , and other factors. A key question, unresolved by our work, is whether the climatic correlates of the size of green spaces in cities are due to the effects of climate per se or if they, instead, reflect correlates between contemporary climate and the social, cultural, and political histories of cities in the Global South 52 . Since urban planning has much inertia, especially in big cities, those choices might be correlated with climate because of the climatic correlates of political histories. It is also possible that these dynamics relate, in part, to the ways in which climate influences vegetation structure. However, this seems less likely given that under non-urban conditions vegetation cover (and hence cooling capacity) is normally positively correlated with mean annual temperature across the globe, opposite to our observed negative relationships for urban systems (Supplementary Fig. 9g ). Still, it is possible that increased temperatures in cities due to the urban heat island effects may lead to temperature-vegetation cover-cooling capacity relationships that differ from those in natural environments 53 , 54 . Indeed, a recent study found that climate warming will put urban forests at risk, and the risk is disproportionately higher in the Global South 55 .

Our model serves as a starting point for unraveling the mechanisms underlying global cooling inequality. We cannot rule out the possibility that other unconsidered factors correlated with the studied variables play important roles. We invite systematic studies incorporating detailed sociocultural and ecological variables to address this question across scales.

Potential of enhancing cooling and reducing inequality

Can we reduce the inequality in cooling capacity and benefits that we have discovered among the world’s largest cities? Nuanced assessments of the potential to improve cooling mitigation require comprehensive considerations of socioeconomic, cultural, and technological aspects of urban management and policy. It is likely that cities differ greatly in their capacity to implement cooling through green infrastructure, whether as a function of culture, governance, policy or some mix thereof. However, any practical attempts to achieve greater cooling will occur in the context of the realities of climate and existing land use. To understand these realities, we modeled the maximum additional cooling capacity that is possible in cities, given existing constraints. We assume that this capacity depends on the quality (cooling efficiency) and quantity of urban green infrastructure. Our approach provides a straightforward metric of the cooling that could be achieved if all parts of a city’s green infrastructure were to be enhanced systematically.

The positive outlook is that our analyses suggest a considerable potential of improving cooling capacity by optimizing urban green infrastructure. An obvious way is through increases in urban green infrastructure quantity. We employ an approach in which we consider each local climate zone 56 to have a maximum NDVI and cooling efficiency (see Methods). For a given local climate zone, the city with the largest NDVI values or cooling efficiency sets the regional upper bounds for urban green infrastructure quantities or quality that can be achieved. Notably, these maxima are below the maxima for forests or other non-urban spaces for the simple reason that, as currently imagined, cities must contain gray (non-green) spaces in the form of roads and buildings. In this context, we conduct a thought experiment. What if we could systematically increase NDVI of all grid cells in each city, per local climate zone type, to a level corresponding to the median NDVI of grid cells in that upper bound city while keeping cooling efficiency unchanged (see Methods). If we were able to achieve this goal, the cooling capacity of cities would increase by ~2.4 °C worldwide. The increase would be even greater, ~3.8°C, if the 90th percentile (within the reference maximum city) was reached (Fig. 5a ). The potential for cooling benefit to the average urban resident is similar to that of cooling capacity (Supplementary Fig. 10a ). There is also potential to reduce urban temperatures if we can enhance cooling efficiency. However, the benefits of increases in cooling efficiency are modest (~1.5 °C increases at the 90th percentile of regional upper bounds) when holding urban green infrastructure quantity constant. In theory, if we could maximize both quantity and cooling efficiency of urban green infrastructure (to 90th percentiles of their regional upper bounds respectively), we would yield increases in cooling capacity and benefit up to ~10 °C, much higher than enhancing green space area or cooling efficiency alone (Fig. 5a , Supplementary Fig. 10a ). Notably, such co-maximization of green space area and cooling efficiency would substantially reduce global inequality to Gini <0.1 (Fig. 5b , Supplementary Fig. 10b ). Our analyses thus provide an important suggestion that enhancing both green space quantity and quality can yield a synergistic effect leading to much larger gains than any single aspect alone.

a The potential of enhancing cooling capacity via either enhancing urban green infrastructure quality (i.e., cooling efficiency) while holding quantity (i.e., green space area) fixed (yellow), or enhancing quantity while holding quality fixed (blue) is much lower than that of enhancing both quantity and quality (green). The x-axis indicates the targets of enhancing urban green infrastructure quantity and/or quality relative to the 50–90th percentiles of NDVI or cooling efficiency, see Methods). The dashed horizontal lines indicate the median cooling capacity of current cities. Data are presented as median values with the colored bands corresponding to 25–75th percentiles. b The potential of reducing cooling capacity inequality is also higher when enhancing both urban green infrastructure quantity and quality. The Gini index weighted by population density is used to measure inequality. Similar results were found for cooling benefit (Supplementary Fig. 10 ).

Different estimates of cooling capacity potential may be reached based on varying estimates and assumptions regarding the maximum possible quantity and quality of urban green infrastructure. There is no single, simple way to make these estimates, especially considering the huge between-city differences in society, culture, and structure across the globe. Our example case (above) begins from the upper bound city’s median NDVI, taking into account different local climate zone types and background climate regions (regional upper bounds). This is based on the assumption that for cities within the same climate regions, their average green space quantity may serve as an attainable target. Still, urban planning is often made at the level of individual cities, often only implemented to a limited extent and made with limited consideration of cities in other regions and countries. A potentially more realistic reference may be taken from the existing green infrastructure (again, per local climate zone type) within each particular city itself (see Methods): if a city’s sparsely vegetated areas was systematically elevated to the levels of 50–90th percentiles of NDVI within their corresponding local climate zones within the city, cooling capacity would still increase, but only by 0.5–1.5 °C and with only slightly reduced inequalities among cities (Supplementary Fig. 11 ). This highlights that ambitious policies, inspired by the greener cities worldwide, are necessary to realize the large cooling potential in urban green infrastructure.

In summary, our results demonstrate clear inequality in the extent to which urban green infrastructure cools cities and their denizens between the Global North and South. Much attention has been paid to the global inequality of indoor heat adaptation arising from the inequality of resources (e.g., less affordable air conditioning and more frequent power shortages in the Global South) 36 , 57 , 58 , 59 . Our results suggest that the inequality in outdoor adaptation is particularly concerning, especially as urban populations in the Global South are growing rapidly and are likely to face the most severe future temperature extremes 60 .

Previous studies have been focusing on characterizing urban heat island effects, urban vegetation patterns, resident exposure, and cooling effects in particular cities 26 , 28 , 34 , 61 , regions 22 , 25 , 62 , or continents 32 , 44 , 63 . Recent studies start looking at global patterns with respect to cooling efficiency or green space exposure 35 , 45 , 64 , 65 . Our approach is one drawn from the fields of large-scale ecology and macroecology. This approach is complementary to and, indeed, can, in the future, be combined with (1) mechanism driven biophysical models 66 , 67 to predict the influence of the composition and climate of green spaces on their cooling efficiency, (2) social theory aimed at understanding the factors that govern the amount of green space in cities as well as the disparity among cities 68 , (3) economic models of the effects of policy changes on the amount of greenspace and even (4) artist-driven projects that seek to understand the ways in which we might reimagine future cities 69 . Our simple explanatory model is, ultimately, one lens on a complex, global phenomenon.

Our results convey some positive outlook in that there is considerable potential to strengthen the cooling capability of cities and to reduce inequalities in cooling capacities at the same time. Realizing this nature-based solution, however, will be challenging. First, enhancing urban green infrastructure requires massive investments, which are more difficult to achieve in Global South cities. Second, it also requires smart planning strategies and advanced urban design and greening technologies 37 , 70 , 71 , 72 . Spatial planning of urban green spaces needs to consider not only the cooling amelioration effect, but also their multifunctional aspects that involve multiple ecosystem services, mental health benefits, accessibility, and security 73 . In theory, a city can maximize its cooling while also maximizing density through the combination of high-density living, ground-level green spaces, and vertical and rooftop gardens (or even forests). In practice, the current cities with the most green spaces tend to be lower-density cities 74 (Supplementary Fig. 12 ). Still, innovation and implementation of new technologies that allow green spaces and high-density living to be combined have the potential to reduce or disconnect the negative relationship between green space area and population density 71 , 75 . However, this development has yet to be realized. Another dimension of green spaces that deserves more attention is the geography of green spaces relative to where people are concentrated within cities. A critical question is how best should we distribute green spaces within cities to maximize cooling efficiency 76 and minimize within-city cooling inequality towards social equity 77 ? Last but not least, it is crucial to design and manage urban green spaces to be as resilient as possible to future climate stress 78 . For many cities, green infrastructure is likely to remain the primary means people will have to rely on to mitigate the escalating urban outdoor heat stress in the coming decades 79 .

We used the world population data from the World’s Cities in 2018 Data Booklet 80 to select 502 major cities with population over 1 million people (see Supplementary Data 1 for the complete list of the studied cities). Cities are divided into the Global North and Global South based on the Human Development Index (HDI) from the Human Development Report 2019 81 . For each selected city, we used the 2018 Global Artificial Impervious Area (GAIA) data at 30 m resolution 82 to determine its geographic extent. The derived urban boundary polygons thus encompass a majority of the built-up areas and urban residents. In using this approach, rather than urban administrative boundaries, we can focus on the relatively densely populated areas where cooling mitigation is most needed, and exclude areas dominated by (semi) natural landscapes that may bias the subsequent quantifications of the cooling effect. Our analyses on the cooling effect were conducted at the 100 m spatial resolution using Landsat data and WorldPop Global Project Population Data of 2018 83 . In order to test for the robustness of the results to coarser spatial scales, we also repeated the analyses at 1 km resolution using MODIS data, which have been extensively used for quantifying urban heat island effects and cooling mitigation 44 , 45 , 51 . We discarded the five cities with sizes <30 km 2 as they were too small for us to estimate their cooling efficiency based on linear regression (see section below for details). We combined closely located cities that form contiguous urban areas or urban agglomerations, if their urban boundary polygons from GAIA merged (e.g., Phoenix and Mesa in the United States were combined). Our approach yielded 468 polygons, each representing a major urbanized area that were the basis for all subsequent analyses. Because large water bodies can exert substantial and confounding cooling effects, we excluded permanent water bodies including lakes, reservoirs, rivers, and oceans using the Copernicus Global Land Service (CGLS) Land Cover data for 2018 at 10 m resolution 84 .

Quantifying the cooling effect

As a first step, we calculated cooling efficiency for each studied city within the GAIA-derived urban boundary. Cooling efficiency quantifies the extent to which a given area of green spaces in a city can reduce temperatures. It is a measure of the effectiveness (quality) of urban green spaces in terms of heat amelioration. Cooling efficiency is typically measured by calculating the slope of the relationship between remotely-sensed land surface temperature (LST) and vegetation cover through ordinary least square regression 42 , 44 , 45 . It is known that cooling efficiency varies between cities. Influencing factors might include background climate 29 , species composition 30 , 85 , landscape configuration 28 , topography 86 , proximity to large water bodies 33 , 87 , urban morphology 88 , and city management practices 31 . However, the mechanism underlying the global pattern of cooling efficiency remains unclear.

We used Landsat satellite data provided by the United States Geological Survey (USGS) to calculate the cooling efficiency of each studied city. We used the cloud-free Landsat 8 Level 2 LST and NDVI data. For each city we calculated the mean LST in each month of 2018 to identify the hottest month, and then derived the hottest month LST; we used the cloud-free Landsat 8 data to calculate the mean NDVI for the hottest month correspondingly.

We quantified cooling efficiency for different local climate zones 56 separately for each city, to account for within-city variability of thermal environments. To this end, we used the Copernicus Global Land Service data (CGLS) 84 and Global Human Settlement Layers (GHSL) Built-up height data 89 of 2018 at the 100 m resolution to identify five types of local climate zones: non-tree vegetation (shrubs, herbaceous vegetation, and cultivated vegetation according to the CGLS classification system), low-rise buildings (built up and bare according to the CGLS classification system, with building heights ≤10 m according to the GHSL data), medium-high-rise buildings (built up and bare areas with building heights >10 m), open tree cover (open forest with tree cover 15–70% according to the CGLS system), and closed tree cover (closed forest with tree cover >70%).

For each local climate zone type in each city, we constructed a regression model with NDVI as the predictor variable and LST as the response variable (using the ordinary least square method). We took into account the potential confounding factors including topographic elevation (derived from MERIT DEM dataset 90 ), building height (derived from the GHSL dataset 89 ), and distance to water bodies (derived from the GSHHG dataset 91 ), the model thus became: LST ~ NDVI + topography + building height + distance to water. Cooling efficiency was calculated as the absolute value of the regression coefficient of NDVI, after correcting for those confounding factors. To account for the multi-collinearity issue, we conducted variable selection based on the variance inflation factor (VIF) to achieve VIF < 5. Before the analysis, we discarded low-quality Landsat pixels, and filtered out the pixels with NDVI < 0 (normally less than 1% in a single city). Cooling efficiency is known to be influenced by within-city heterogeneity 92 , 93 , and, as a result, might sometimes better fit non-linear relationships at local scales 65 , 76 . However, our central aim is to assess global cooling inequality based on generalized relationships that fit the majority of global cities. Previous studies have shown that linear relationships can do this job 42 , 44 , 45 , therefore, here we used linear models to assess cooling efficiency.

As a second step, we calculated the cooling capacity of each city. Cooling capacity is a positive function of the magnitude of cooling efficiency and the proportional area of green spaces in a city and is calculated based on NDVI and the derived cooling efficiency (Eq. 1 , Supplementary Fig. 13 ):

where CC lcz and CE lcz are the cooling capacity and cooling efficiency for a given local climate zone type in a city, respectively; NDVI i is the mean NDVI for 100-m grid cell i ; NDVI min is the minimum NDVI across the city; and n is the total number of grid cells within the local climate zone. Local cooling capacity for each grid cell i (Fig. 1 , Supplementary Fig. 7 ) can be derived in this way as well (Supplementary Fig. 13 ). For a particular city, cooling capacity may be dependent on the spatial configuration of its land use/cover 28 , 94 , but here we condensed cooling capacity to city average (Eq. 2 ), thus did not take into account these local-scale factors.

where CC is the average cooling capacity of a city; n lcz is the number of grid cells of the local climate zone; m is the total number of grid cells within the whole city.

As a third step, we calculated the cooling benefit realized by an average urban resident (cooling benefit in short) in each city. Cooling benefit depends not only on the cooling capacity of a city, but also on where people live within a city relative to greener or grayer areas of the city. For example, cooling benefits in a city might be low even if the cooling capacity is high if the green parts and the dense-population parts of a city are inversely correlated. Here, we are calculating these averages while aware that in any particular city the exposure of a particular person will depend on the distribution of green spaces in a city, and the occupation, movement trajectories of a person, etc. On the scale of a city, we calculated cooling benefit following a previous study 35 , that is, simply adding a weight term of population size per 100-m grid cell into cooling capacity in Eq. ( 1 ):

Where CB lcz is the cooling benefit of a given local climate zone type in a specific city, pop i is the number of people within grid cell i , $\overline{{pop}}$ is the mean population of the city.

Where CB is the average cooling benefit of a city. The population data were obtained from the 100-m resolution WorldPop Global Project Population Data of 2018 83 . Local cooling benefit for a given grid cell i can be calculated in a similar way, i.e., local cooling capacity multiplied by a weight term of local population density relative to mean population density. Local cooling benefits were mapped for example cities for the purpose of illustrating the effect of population spatial distribution (Fig. 1 , Supplementary Fig. 7 ), but their patterns were not examined here.

Based on the aforementioned three key variables quantified at 100 m grid cells, we conducted multivariate analyses to examine if and to what extent cooling efficiency and cooling benefit are shaped by essential natural and socioeconomic factors, including background climate (mean annual temperature from ECMWF ERA5 dataset 95 and precipitation from TerraClimate dataset 96 ), topography (elevation range 90 ), and GDP per capita 97 , with city size (geographic extent) corrected for. We did not include humidity because it is strongly correlated with temperature and precipitation, causing serious multi-collinearity problems. We used piecewise structural equation modeling to test the direct effects of these factors and indirect effects via influencing cooling efficiency and vegetation cover (Fig. 4c , Supplementary Fig. 8c ). To account for the potential influence of spatial autocorrelation, we used spatially autoregressive models (SAR) to test for the robustness of the observed effects of natural and socioeconomic factors on cooling capacity and benefit (Supplementary Fig. 14 ).

Testing for robustness

We conducted the following additional analyses to test for robustness. We obtained consistent results from these robustness analyses.

(1) We looked at the mean hottest-month LST and NDVI within 3 years (2017-2019) to check the consistency between the results based on relatively short (1 year) vs. long (3-year average) time periods (Supplementary Fig. 15 ).

(2) We carried out the approach at a coarser spatial scale of 1 km, using MODIS-derived NDVI and LST, as well as the population data 83 in the hottest month of 2018. In line with our finer-scale analysis of Landsat data, we selected the hottest month and excluded low-quality grids affected by cloud cover and water bodies 98 (water cover > 20% in 1 × 1 km 2 grid cells) of MODIS LST, and calculated the mean NDVI for the hottest month. We ultimately obtained 441 cities (or urban agglomerations) for analysis. At the 1 km resolution, some local climate zone types would yield insufficient samples for constructing cooling efficiency models. Therefore, instead of identifying local climate zone explicitly, we took an indirect approach to account for local climate confounding factors, that is, we constructed a multiple regression model for a whole city incorporating the hottest-month local temperature 95 , precipitation 96 , and humidity (based on NASA FLDAS dataset 99 ), albedo (derived from the MODIS MCD43A3 product 100 ), aerosol loading (derived from the MODIS MCD19A2 product 101 ), wind speed (based on TerraClimate dataset 96 ), topography elevation 90 , distance to water 91 , urban morphology (building height 102 ), and human activity intensity (VIIRS nighttime light data as a proxy indicator 103 ). We used the absolute value of the linear regression coefficient of NDVI as the cooling efficiency of the whole city (model: LST ~ NDVI + temperature + precipitation + humidity + distance to water + topography + building height + albedo + aerosol + wind speed + nighttime light), and calculated cooling capacity and cooling benefit based on the same method. Variable selection was conducted using the criterion of VIF < 5.

Our results indicated that MODIS-based cooling capacity and cooling benefit are significantly correlated with the Landsat-based counterparts (Supplementary Fig. 16 ); importantly, the gap between the Global South and North cities is around two-fold, close to the result from the Landsat-based result (Supplementary Fig. 17 ).

(3) For the calculation of cooling benefit, we considered different spatial scales of human accessibility to green spaces: assuming the population in each 100 × 100 m 2 grid cell could access to green spaces within neighborhoods of certain extents, we calculated cooling benefit by replacing NDVI i in Eq. ( 3 ) with mean NDVI within the 300 × 300 m 2 and 500 × 500 m 2 extents centered at the focal grid cell (Supplementary Fig. 18 ).

(4) Considering cities may vary in minimum NDVI, we assessed if this variation could affect resulting cooling capacity patterns. To this end, we calculated the cooling capacity for each studied city using NDVI = 0 as the reference (i.e., using NDVI = 0 instead of minimum NDVI in Supplementary Fig. 13b ), and correlated it with that using minimum NDVI as the reference (Supplementary Fig. 19 ).

Quantifying between-city inequality

Inequalities in access to the benefits of green spaces in cities exist within cities, as is increasingly well-documented 104 . Here, we focus instead on the inequalities among cities. We used the Gini coefficient to measure the inequality in cooling capacity and cooling benefit between all studied cities across the globe as well as between Global North or South cities. We calculated Gini using the population-density weighted method (Fig. 5b ), as well as the unweighted and population-size weighted methods (Supplementary Fig. 20 ).

Estimating the potential for more effective and equal cooling amelioration

We estimated the potential of enhancing cooling amelioration based on the assumptions that urban green space quality (cooling efficiency) and quantity (NDVI) can be increased to different levels, and that relative spatial distributions of green spaces and population can be idealized (so that their spatial matches can maximize cooling benefit). We assumed that macro-climate conditions act as the constraints of vegetation cover and cooling efficiency. We calculated the 50th, 60th, 70th, 80th, and 90th percentiles of NDVI within each type of local climate zone of each city. For a given local climate zone type, we obtained the city with the highest NDVI per percentile value as the regional upper bounds of urban green infrastructure quantity. The regional upper bounds of cooling efficiency are derived in a similar way. For each local climate zone in a city, we generated a potential NDVI distribution where all grid cells reach the regional upper bound values for the 50th, 60th, 70th, 80th, or 90th percentile of urban green space quantity or quality, respectively. NDVI values below these percentiles were increased, whereas those above these percentiles remained unchanged. The potential estimates are essentially dependent on the references, i.e., the optimal cooling efficiency and NDVI that a given city can reach. However, such references are obviously difficult to determine, because complex natural and socioeconomic conditions could play important roles in determining those cooling optima, and the dominant factors are unknown at a global scale. We employed the simplifying assumption that background climate could act as an essential constraint according to our results. We therefore used the Köppen climate classification system 105 to determine the reference separately in each climate region (tropical, arid, temperate, and continental climate regions were involved for all studied cities).

We calculated potential cooling capacity and cooling benefit based on these potential NDVI maps (Fixed cooling efficiency in Fig. 5 ). We then calculated the potentials if cooling efficiency of each city can be enhanced to 50–90th percentile across all urban local climate zones within the corresponding biogeographic region (Fixed green space area in Fig. 5 ). We also calculated the potentials if both NDVI and cooling efficiency were enhanced (Enhancing both in Fig. 5) to a certain corresponding level (i.e., i th percentile NDVI + i th percentile cooling efficiency). We examined if there are additional effects of idealizing relative spatial distributions of urban green spaces and humans on cooling benefits. To this end, the pixel values of NDVI or population amount remained unchanged, but their one-to-one correspondences were based on their ranking: the largest population corresponds to the highest NDVI, and so forth. Under each scenario, we calculated cooling capacity and cooling benefit for each city, and the between-city inequality was measured by the Gini coefficient.

We used the Google Earth Engine to process the spatial data. The statistical analyses were conducted using R v4.3.3 106 , with car v3.1-2 107 , piecewiseSEM v2.1.2 108 , and ineq v0.2-13 109 packages. The global maps of cooling were created using the ArcGIS v10.3 software.

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.

Data availability

City population statistics data is collected from the Population Division of the Department of Economic and Social Affairs of the United Nations ( https://www.un.org/development/desa/pd/content/worlds-cities-2018-data-booklet ). Global North-South division is based on Human Development Report 2019 which from United Nations Development Programme ( https://hdr.undp.org/content/human-development-report-2019 ). Global urban boundaries from GAIA data are available from Star Cloud Data Service Platform ( https://data-starcloud.pcl.ac.cn/resource/14 ) . Global water data is derived from 2018 Copernicus Global Land Service (CGLS 100-m) data ( https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_Landcover_100m_Proba-V-C3_Global ), European Space Agency (ESA) WorldCover 10 m 2020 product ( https://developers.google.com/earth-engine/datasets/catalog/ESA_WorldCover_v100 ), and GSHHG (A Global Self-consistent, Hierarchical, High-resolution Geography Database) at https://www.soest.hawaii.edu/pwessel/gshhg/ . Landsat 8 LST and NDVI data with 30 m resolution are available at https://developers.google.com/earth-engine/datasets/catalog/LANDSAT_LC08_C02_T1_L2 . Land surface temperature (LST) data with 1 km from MODIS Aqua product (MYD11A1) is available at https://developers.google.com/earth-engine/datasets/catalog/MODIS_061_MYD11A1 . NDVI (1 km) dataset from MYD13A2 is available at https://developers.google.com/earth-engine/datasets/catalog/MODIS_061_MYD13A2 . Population data (100 m) is derived from WorldPop ( https://developers.google.com/earth-engine/datasets/catalog/WorldPop_GP_100m_pop ). Local climate zones are also based on 2018 CGLS data ( https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_Landcover_100m_Proba-V-C3_Global ), and built-up height data is available from Global Human Settlement Layers (GHSL, 100 m) ( https://developers.google.com/earth-engine/datasets/catalog/JRC_GHSL_P2023A_GHS_BUILT_H ). Temperature data is calculated from ERA5-Land Monthly Aggregated dataset ( https://developers.google.com/earth-engine/datasets/catalog/ECMWF_ERA5_LAND_MONTHLY_AGGR ). Precipitation and wind data are calculated from TerraClimate (Monthly Climate and Climatic Water Balance for Global Terrestrial Surfaces, University of Idaho) ( https://developers.google.com/earth-engine/datasets/catalog/IDAHO_EPSCOR_TERRACLIMATE ). Humidity data is calculated from Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System ( https://developers.google.com/earth-engine/datasets/catalog/NASA_FLDAS_NOAH01_C_GL_M_V001 ). Topography data from MERIT DEM (Multi-Error-Removed Improved-Terrain DEM) product is available at https://developers.google.com/earth-engine/datasets/catalog/MERIT_DEM_v1_0_3 . GDP from Gross Domestic Product and Human Development Index dataset is available at https://doi.org/10.5061/dryad.dk1j0 . VIIRS nighttime light data is available at https://developers.google.com/earth-engine/datasets/catalog/NOAA_VIIRS_DNB_MONTHLY_V1_VCMSLCFG . City building volume data from Global 3D Building Structure (1 km) is available at https://doi.org/10.34894/4QAGYL . Albedo data is derived from the MODIS MCD43A3 product ( https://developers.google.com/earth-engine/datasets/catalog/MODIS_061_MCD43A3 ), and aerosol data is derived from the MODIS MCD19A2 product ( https://developers.google.com/earth-engine/datasets/catalog/MODIS_061_MCD19A2_GRANULES ). All data used for generating the results are publicly available at https://doi.org/10.6084/m9.figshare.26340592.v1 .

Code availability

The codes used for data collection and analyses are publicly available at https://doi.org/10.6084/m9.figshare.26340592.v1 .

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Acknowledgements

We thank all the data providers. We thank Marten Scheffer for valuable discussion. C.X. is supported by the National Natural Science Foundation of China (Grant No. 32061143014). J.-C.S. was supported by Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), funded by Danish National Research Foundation (grant DNRF173), and his VILLUM Investigator project “Biodiversity Dynamics in a Changing World”, funded by VILLUM FONDEN (grant 16549). W.Z. was supported by the National Science Foundation of China through Grant No. 42225104. T.M.L. and J.F.A. are supported by the Open Society Foundations (OR2021-82956). W.J.R. is supported by the funding received from Roger Worthington.

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Y.L., S.N.T., R.R.D., and C.X. designed the study. Y.L. collected the data, generated the code, performed the analyses, and produced the figures with inputs from J.-C.S., W.Z., K.Z., J.F.A., T.M.L., W.J.R., Z.Y., S.N.T., R.R.D. and C.X. Y.L., S.N.T., R.R.D. and C.X. wrote the first draft with inputs from J.-C.S., W.Z., K.Z., J.F.A., T.M.L., W.J.R., and Z.Y. All coauthors interpreted the results and revised the manuscript.

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Li, Y., Svenning, JC., Zhou, W. et al. Green spaces provide substantial but unequal urban cooling globally. Nat Commun 15 , 7108 (2024). https://doi.org/10.1038/s41467-024-51355-0

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Introduction
Finding sources

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Tools and resources, a quick guide to working with sources.

Working with sources is an important skill that you’ll need throughout your academic career.

It includes knowing how to find relevant sources, assessing their authority and credibility, and understanding how to integrate sources into your work with proper referencing.

This quick guide will help you get started!

Finding relevant sources

Sources commonly used in academic writing include academic journals, scholarly books, websites, newspapers, and encyclopedias. There are three main places to look for such sources:

Research databases: Databases can be general or subject-specific. To get started, check out this list of databases by academic discipline . Another good starting point is Google Scholar .
Your institution’s library: Use your library’s database to narrow down your search using keywords to find relevant articles, books, and newspapers matching your topic.
Other online resources: Consult popular online sources like websites, blogs, or Wikipedia to find background information. Be sure to carefully evaluate the credibility of those online sources.

When using academic databases or search engines, you can use Boolean operators to refine your results.

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In academic writing, your sources should be credible, up to date, and relevant to your research topic. Useful approaches to evaluating sources include the CRAAP test and lateral reading.

CRAAP is an abbreviation that reminds you of a set of questions to ask yourself when evaluating information.

Currency: Does the source reflect recent research?
Relevance: Is the source related to your research topic?
Authority: Is it a respected publication? Is the author an expert in their field?
Accuracy: Does the source support its arguments and conclusions with evidence?
Purpose: What is the author’s intention?

Lateral reading

Lateral reading means comparing your source to other sources. This allows you to:

Verify evidence
Contextualize information
Find potential weaknesses

If a source is using methods or drawing conclusions that are incompatible with other research in its field, it may not be reliable.

Integrating sources into your work

Once you have found information that you want to include in your paper, signal phrases can help you to introduce it. Here are a few examples:

Function	Example sentence	Signal words and phrases
You present the author’s position neutrally, without any special emphasis.	recent research, food services are responsible for one-third of anthropogenic greenhouse gas emissions.	According to, analyzes, asks, describes, discusses, explains, in the words of, notes, observes, points out, reports, writes
A position is taken in agreement with what came before.	Recent research Einstein’s theory of general relativity by observing light from behind a black hole.	Agrees, confirms, endorses, reinforces, promotes, supports
A position is taken for or against something, with the implication that the debate is ongoing.	Allen Ginsberg artistic revision …	Argues, contends, denies, insists, maintains

Following the signal phrase, you can choose to quote, paraphrase or summarize the source.

Quoting : This means including the exact words of another source in your paper. The quoted text must be enclosed in quotation marks or (for longer quotes) presented as a block quote . Quote a source when the meaning is difficult to convey in different words or when you want to analyze the language itself.
Paraphrasing : This means putting another person’s ideas into your own words. It allows you to integrate sources more smoothly into your text, maintaining a consistent voice. It also shows that you have understood the meaning of the source.
Summarizing : This means giving an overview of the essential points of a source. Summaries should be much shorter than the original text. You should describe the key points in your own words and not quote from the original text.

Whenever you quote, paraphrase, or summarize a source, you must include a citation crediting the original author.

Citing your sources is important because it:

Allows you to avoid plagiarism
Establishes the credentials of your sources
Backs up your arguments with evidence
Allows your reader to verify the legitimacy of your conclusions

The most common citation styles are APA, MLA, and Chicago style. Each citation style has specific rules for formatting citations.

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References in Research
Learn how to cite sources in research papers, theses, dissertations, and other scholarly publications. Find out the common types of references, formats, and examples for books, journal articles, web sources, and more.
Academic Guides: Reference List: Common Reference List Examples
For example, you are citing study notes titled "Health Effects of Exposure to Forest Fires," but you do not know the author's name, your reference entry will look like this: Health effects of exposure to forest fires [Lecture notes]. (2005). Walden University Canvas. https://waldenu.instructure.com.
PDF 7th edition Common Reference Examples Guide
This guide contains examples of common types of APA Style references. Section numbers indicate where to find the examples in the Publication Manual of the American Psychological Association (7th ed.). More information on references and reference examples are in Chapters 9 and 10 of the Publication Manual as well as the Concise Guide to APA ...
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References
Learn how to format references in APA Style, a widely used citation system in the social sciences. Find examples of references for different types of sources and tips for accuracy and consistency.
APA Formatting and Style Guide (7th Edition)
Reference List. Resources on writing an APA style reference list, including citation formats. Basic Rules Basic guidelines for formatting the reference list at the end of a standard APA research paper Author/Authors Rules for handling works by a single author or multiple authors that apply to all APA-style references in your reference list ...
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APA Style is widely used by students, researchers, and professionals in the social and behavioral sciences. Scribbr's free citation generator automatically generates accurate references and in-text citations. This citation guide outlines the most important citation guidelines from the 7th edition APA Publication Manual (2020).
A Quick Guide to Harvard Referencing
When you cite a source with up to three authors, cite all authors' names. For four or more authors, list only the first name, followed by ' et al. ': Number of authors. In-text citation example. 1 author. (Davis, 2019) 2 authors. (Davis and Barrett, 2019) 3 authors.
Citation Styles Guide
The Bluebook: A Uniform System of Citation is the main style guide for legal citations in the US. It's widely used in law, and also when legal materials need to be cited in other disciplines. Bluebook footnote citation. 1 David E. Pozen, Freedom of Information Beyond the Freedom of Information Act, 165, U. P🇦 .
References: How to Cite and List Correctly
If a single reference points to more than one source, list the source numbers in a series, for example, as 1,3,6. Use a dash to separate more than two numbers as 1−3, if these form a sequence. However, use a comma to separate two numbers as 1,3 (without space in between), if these do not form a sequence.
Citations, References and Bibliography in Research Papers [Beginner's
The essential difference between citations and references is that citations lead a reader to the source of information, while references provide the reader with detailed information regarding that particular source. Bibliography in research papers: A bibliography in research paper is a list of sources that appears at the end of a research paper ...
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Here's one example of writing references in research papers - 'Nature 171: 737' is a code that, if you know how to decipher it, tells you that it means an article published in Nature (a weekly journal published from the UK) that begins on page 737 of volume 171 of that journal. However, it does not tell you what the article was about ...
How to Cite Sources in APA Citation Format
1. APA Referencing Basics: Reference List. A reference list is a complete list of references used in a piece of writing including the author name, date of publication, title and more. An APA reference list must: Be on a new page at the end of the document. Be centred
Research Guides: Citing Sources: Sample Reference List Citations
Examples. 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 ...
Reference List: Basic Rules
Reference List: Basic Rules. This resourse, revised according to the 7 th edition APA Publication Manual, offers basic guidelines for formatting the reference list at the end of a standard APA research paper. Most sources follow fairly straightforward rules. However, because sources obtained from academic journals carry special weight in research writing, these sources are subject to special ...
How to Create or Generate APA Reference Entries (7th edition)
Separate the names of multiple authors with commas. Before the last author's name, you should also insert an ampersand (&). A reference entry may contain up to 20 authors. If there are more than 20, list the first 19 authors, followed by an ellipsis (. . .) and the last author's name. Andreff, W., & Staudohar, P. D.
Journal article references
Narrative citation: Grady et al. (2019) If a journal article has a DOI, include the DOI in the reference. Always include the issue number for a journal article. 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 ...
Free Harvard Referencing Generator [Updated for 2024]
A Harvard Referencing Generator is a tool that automatically generates formatted academic references in the Harvard style. It takes in relevant details about a source -- usually critical information like author names, article titles, publish dates, and URLs -- and adds the correct punctuation and formatting required by the Harvard referencing ...
Academic Guides: References: Common Reference List Examples
At the end of the entry, place the date of the original publication inside parenthesis along with the note "original work published.". For in-text citations of republished work, use both dates in the parenthetical citation, original date first with a slash separating the years, as in this example: Freud (1923/1961).
Setting Up the APA Reference Page
On the APA reference page, you list all the sources that you've cited in your paper. The list starts on a new page right after the body text. Follow these instructions to set up your APA reference page: Place the section label "References" in bold at the top of the page (centered). Order the references alphabetically. Double-space all text.
FREE Reference Generator: Accurate & Easy-to-Use
To use the reference generator, simply: Select your style from Harvard, APA, OSCOLA and many more*. Choose the type of source you would like to cite (e.g. website, book, journal, video) Enter the URL, DOI, ISBN, title, or other unique source information to find your source. Click the 'Cite' button on the reference generator.
Green spaces provide substantial but unequal urban cooling ...
A 1.5-fold gap exists in green space cooling adaptation between cities in the Global South and North. Enhancing urban green space quality and quantity offers vast potential for improving outdoor ...
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References in Research – Types, Examples and Writing Guide

References in Research

Types of References

Journal Articles

Web sources

Formats of References

APA (American Psychological Association) Style

MLA (Modern Language Association) Style

Chicago Manual of Style

Harvard Style

Vancouver Style

Turabian Style

IEEE (Institute of Electrical and Electronics Engineers) Style

ACS (American Chemical Society) Style

AMA (American Medical Association) Style

ASCE (American Society of Civil Engineers) Style

CSE (Council of Science Editors) Style

Bluebook Style

Oxford Style

AAA (American Anthropological Association) Style

AIP (American Institute of Physics) Style

References Writing Guide

Purpose of References in Research

Importance of References in Research

Advantages of References in Research

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Muhammad Hassan

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Types of references in research papers

How to write references in research papers

How to add references in a research paper: Key elements

Sequence of the elements that make up reference s in research papers

Punctuation to separate the elements that make up references in research papers

Typography of references in research papers

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