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How do I use APA Citation Style

A guide with examples for references and in-text citation

Secondary Sources

Use secondary sources very sparingly, usually only when you cannot obtain the original work (e.g. it is out-of-print). Where possible, you should read the original work.

In your reference list, give the details of the secondary work. In the text, name the original work and give a citation for the secondary source. (Section 6.17).

Arrow found that the role of leaders in the social choice tradition derives from the well-known instability in social choice (as cited in Ahlquist & Levi, 2011).

Reference list for example above:

Ahlquist, J. S. & Levi, M. (2011). Leadership: What it means, what it does, and what we want to know about it. Annual Review of Political Science, 14, 1-24.

In-text: (Ahlquist & Levi, 2011)

Secondary in-text citation: (as cited in Ahlquist & Levi, 2011)

Two or more works by the same author, same year

"Reference twins," or two (or more) references by the same author (or the same group of authors listed in the same order) published in the same year, are organised n the reference list alphabetically by the title of the article or chapter. Assign letter suffixes to the years to differentiate between or among the references.  Read more here.


Koriat, A. (2008a). Easy comes, easy goes? The link between learning and remembering and its exploitation in metacognition. Memory & Cognition, 36, 416-428.

In-text: (Koriat, 2008a).


Koriat, A. (2008b). Subjective confidence in one’s answers: The consensuality principle. Journal of Experimental Psychology: Learning, Memory, and Cognition, 34, 945-959.

In-text: (Koriat, 2008b).

Reference with no author

If there is no author for a particular webpage or source, move the title to the first position.  (However, before doing this, DOUBLE CHECK to make sure there really is no author.  For more information, read this APA Style blog post.)


All 33 Chile miners freed in flawless rescue. (2010, October 13). Retrieved from

In-text: ("All 33 Chile Miners Freed," 2010).


Author names: Cultural variations

The APA Style blog has some helpful articles on cultural variations in names and name order.  Please refer to the following posts:

Citing works generated by AI tools

The APA Style team has written a blog post on How to cite ChatGPT in April 2023. The current recommendations are specific to quoting or reproducing text created by AI Tools. 

The APA Style team provide an example for reference and in-text citations for ChatGPT, formatted as follows:


OpenAI. (2023). ChatGPT (Mar 14 version) [Large language model].


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


The 4 key elements to note are:
Author:    Author of the AI model. This could be a company, such as OpenAI or Google.
Date:      Year of version. The version number is written after the title in parenthesis. OpenAI labels its versions using dates, which in this example turns out to be "Mar 14 version". Other author or publishers may label their versions differently (e.g. Version 2.0)
Title:       Model of the AI tool
Source:  List the URL.


For more information, and questions about citing text generated by ChatGPT and AI tools, refer to the post here.
For an example of citing artwork generated by AI, you may consider our suggestion in this list here.

The use of electronic resources must comply with the Appropriate Use of Electronic Resources Policy and Singapore Management University Acceptable Use Policy