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Citation Styles

This guide lists some major styles that are commonly used by various subject disciplines.

Introduction to the American Psychological Association (APA)

American Psychological Association (APA) is a citation style that is widely used in psychology and social sciences. There are two parts to referencing in APA:

  • In-text citations found within the text of the research paper. The APA style uses "author-date" style for its in-text citation.
  • List of references at the end of the paper.

This guide provides a brief introduction to the APA 7th style for referencing and citing. For more information about this style, please refer to Publication Manual of the APA or the APA Style website.

In-text citations

The table below provides a few examples of how in-text citations may be done based on the number of authors or type of authors. You may wish to refer to Purdue University's OWL (Online Writing Lab) Basics of In-Text Citations for more information or click here for more examples.

  • A work by a single author


The last name of the author and the year of publication are inserted in the text at the appropriate point. ......from theory on bounded rationality (Simon, 1945)

If the name of the author or the date appear as part of the narrative cite only missing information in parentheses.

Simon (1945) highlighted that....

In 1945, Simon highlighted that....

  • A work by two authors 


When a work has two authors, cite both authors each time the reference occurs in the text.

In parenthetical, material join the names with an ampersand (&).

.... as has been shown (Leiter & Maslach, 1998)

In narrative text, join the names with the word :an:  Include "and"  between authors' name in the text. Leiter and Maslach (1998) demonstrated....
  • A work by multiple authors (three or more authors)
Guidelines Examples

When a work has three or more authors, cite only the first author's name, followed by et al. in each citation, including the first, and the year.

Note: "et al" means "and others"

(Kahneman et al., 1991)

Kahneman et al. (1991) found...........

  • Organisation / Corporate as an author
Guidelines Examples

The name of corporate authors are written out each time they appear in a text reference.

(Institute of Mental Health [IMH], 2021)
  • Government agency as an author
Guidelines Examples

The specific government agency responsible for the report is the author of the report, followed by the year.

(Singapore Department of Statistics, 2019)

Reference list

The table below provides a few commonly used sources. For many other examples, please click here.

You may also refer to the Reference List: Basic Rules for more information.

Guidelines Examples
A book with single author

Freud, S. (2003). The uncanny. Penguin Books.

Tall, D. (2013). How humans learn to think mathematically: Exploring the three worlds of mathematics. Cambridge University Press.

A book with multiple authors

Ciccarelli, S. K., & White, J. N. (2009). Psychology (2nd ed.). Prentice Hall.

Silva, B. C., Boscancianu, C. M., & Littvay, L. (2020). Multilevel structural equation modelling. SAGE Publications.

A book with an editor instead of a main author. Use "Eds." if there are two or more editors.

Sternberg, R. J. (Ed.). (2003). Psychologists defying the crowd: stories of those who battled the establishment and won. American Psychological Association.

Book chapter

Davis, D. A. (2008). Freud, Jung, and psychoanalysis. In P. Young-Eisendrath (Ed.), The Cambridge companion to Jung (pp.39-55). Cambridge University Press. 

Ball, T., & Hunter, L. (2013). Supporting access to science and engineering through scientific argumentation. In G. Wells & A. Edwards (Eds.), Pedagogy in higher education: A cultural historical approach (pp. 123-139). Cambridge University Press.

A journal article with single author, with DOI Gallistel, C. R. (2009). The importance of providing the null. Psychological Review, 116(2), 439-454.
A journal article with two or more authors, with DOI

Smith, E. R., & Collins, E. C. (2009). Contextualizing person perception: Distributed social cognition. Psychological Review, 116(2), 343-364

Burgess, M. G., Brough, P., Biggs, A., & Hawkes, A. J. (2020). Why interventions fail: A systematic review of occupational health psychology interventions. International Journal of Stress Management, 27(2), 195-207.

Fukuhara-Makiyama, N., Hayashida, M., Kobayashi, M., Sagara, I., Ogawa, S., Maeda, M., & Shirabe, S. (2021). Personality traits and BMI trends over three years in Japanese university students. PLoS ONE, 16(3), Article e0248833.

Articles from newspapers or magazines

Khalik, S. (2021, July 16). Half of hospitalised Covid-19 patients suffered at least one complication: UK study. The Straits Times.

Kluger, J. (2008, January 28). Why we love. Time, 171(4), 54-60.

Blog post

Linebaugh, R. (2020, March 12). Writing unplugged. Inside Higher Ed.

Crisp, R. (2021, December 14). Putting your philosophical house in order. Practical Ethics.

Data from EIU

Economist Intelligence Unit. (2022). Global forecast data from 2012 to 2026 [Data file]. Retrieved January 12, 2022, from EIU Viewpoint database.

Data from Statista

YouGov. (2021, December 21). Share of people who wore face masks in public places during the COVID-19 pandemic in Singapore from February 2020 to November 2021 [Data set]. Statista.

Government report

Singapore Department of Statistics. (2019). Report on the household expenditure survey 2017/18

Podcast Lamble, K., & Razzell, N. (Hosts). (2021, September 28). What homes to build in a climate-changed world? [Audio podcast]. BBC.
Press release

Singapore Ministry of Health. (2022, January 5). Strengthening our readiness to live with the omicron variant [Press release].


Gage, H. M., & Kriedeman, C. L. (2021). Invasive plant management in Kenai Fjords National Park: 2020 summary report. (Natural Resource Report NPS/KEFJ/NRR—2021/2227). U.S. Department of the Interior, National Park Service.

Statista. (2021). Digital media report 2021.

Statista. (n.d.) Social media marketing worldwide.

United Nations Children’s Fund. The state of the world’s children 2021: On my mind – promoting, protecting and caring for children’s mental health.

Singapore Statute (taking reference from Singapore Academy of Law Style Guide)

Education Act (Cap 87, 2013 Rev Ed) s 61(1) (Singapore).

TED video from YouTube

TED. (2019, June 3). Sleep is your superpower | Matt Walker [Video]. YouTube.

TED video from TED website

Walker, M. (2019, April). Sleep is your superpower [Video]. TED Conferences.


Lau, W. K. (2020). Behaviors maintaining perceptual continuity [Doctoral dissertation, Nanyang Technological University]. Digital Repository of NTU.

Porter, T. (2015). Intellectual humility, mindset and learning [Doctoral dissertation, Stanford University]. ProQuest Dissertations & Theses Global.

Video from Vimeo, YouTube

Three Minute Thesis (3MT). (2021, September 2). 2021 UQ 3MT winner – Rosie Stoke [Video]. Vimeo.

WIRED. (2022, February 22). Statistician answers stats questions from Twitter | Tech Support | WIRED [Video]. YouTube.

Webpage on a news website

Rodriguez-Cayro, K. (2021, October 21). How to help someone experiencing depression for the first time. HuffPost.

Webpage on a website with an organisational group author World Health Organization. (2021, October 26). Bandung: Championing city-level tobacco control

Additional resources