Proper citation is an important component of any APA Style paper. However, many readers believe certain sources aren’t allowed in APA Style, and they write to us looking for a definitive list of what is off limits. Two of the most common questions are about whether it’s okay to cite websites and whether sources have to have been published within a certain time frame to be cited, such as the last 5 or 10 years.
Let’s set the record straight: Anything that a reader can retrieve, you can cite as a source in an APA Style reference list. Things the reader can’t retrieve (like a conversation, an unrecorded webinar, or a personal e-mail) can be cited as personal communications (see PM § 6.20). And there are no limits on the age of sources.
But just because you can cite anything as a source doesn’t mean you should. Rather, APA recommends that sources be reliable, primary accounts that represent the most up-to-date information wherever possible. Let’s look at each of these aspects in more detail.
A reliable source is one you can trust. Two indicators of reliability are the expertise of the author and the vetting standards of the place of publication. For example, an article written by a researcher and published in a peer-reviewed journal is likely to contain reliable information and thus would make a good source. On the other hand, a random website written by an unknown person, for example, is less likely to be reliable, and thus we would not recommend you cite this source unless you have a good reason (e.g., to talk about the source’s unreliability) or you verify the information yourself using other reliable sources.
However, the mere fact that information is published online is not reason to dismiss it as unreliable. Many scientific, medical, and governmental organizations—such as the Centers for Disease Control and Prevention (CDC), National Institutes of Health, U.S. Census Bureau, and even the APA—publish reliable information on their websites and social media sites. Scientists and research organizations might publish blogs or YouTube videos that are worth citing. Evaluate each source on its own merits for reliability when determining whether to cite it in a paper.
A primary source presents information gathered firsthand, such as the results of an experiment or data from a survey. Secondary sources present information secondhand—an example would be a textbook summary of a topic or a Wikipedia article. APA recommends citing primary sources whenever possible, because this allows you to verify the accuracy and completeness of the information yourself rather than rely on someone else to do this for you. Secondary sources can be reliable, but it is a best practice of scholarly writing to investigate for yourself if you can. See here and here for more information on primary and secondary sources.
APA recommends that you use the most up-to-date research you can find on your topic. However, the meaning of up-to-date will vary depending on the field. Some fields develop faster than others, and even within a field, some information will remain relevant for a long time, whereas other information will become outdated. For example, foundational works may be quite old but still worth citing when you are establishing the context for your own work. There is no year-related cutoff where sources must be published within the past x number of years to be used in a paper. Each source must be evaluated on a case-by-case basis to determine whether the information in it is timely and relevant.
If you have further questions about choosing sources for an APA Style paper, leave a comment below.