How should a source be cited if it does not have a date?

In APA style, when citing a source that does not have a publication date, the correct approach is to use "n.d.," which stands for "no date." This notation informs the reader that the author was unable to identify a specific year of publication for the source in question. By using "n.d.," you maintain consistency and clarity in your citation, ensuring that readers understand that the lack of a date is an integral part of the citation.

Using "n/a" is not appropriate in APA citations, as it does not conform to the established conventions of the style. Omitting the date entirely would leave a gap in essential information that could hinder understanding. Lastly, using the year of the last update could lead to inaccuracies, especially if that update does not correlate to the original publication date. Therefore, "n.d." is crucial for providing a clear and accurate representation of the source's availability information.