Digital Object Identifiers
Introduction
A DOI, or digital object identifier, is an alpha-numeric string that is associated with a particular publication. It is similar to a URL (a uniform resource locator), the web link you see in your browser’s address bar. However, a DOI is more stable and will remain permanently attached to a publication.
The APA guidelines suggest that if a source has a DOI, you should include it in the citation, even if you did not access the source online.
Current Guidelines
The American Psychological Association follows the guidelines for DOIs provided by Crossref, the organization that helps publishers create consistent citation linking. A proper DOI should be in the following format (the letter x being a variable number or letter):
https://doi.org/10.xxxx/xxxxxx
Let’s take a closer look at the component parts of a DOI:
Note that every DOI will include the number 10 at the start of the prefix. The next number is at least four digits long and is associated with the registrant, a particular publisher or organization. The suffix consists of any number of letters and numbers.
When citing an online source with a DOI, add it at the end of your citation:
Wittles, Q. (2011). Freud and the art of doodling. Art and Psychology, 19, 22-33. https://doi.org/10.1091/1598300983
Make the link clickable if your writing is published online. Also, make sure you don’t add a period afterwards, as that may mess up the link.
How to Find a DOI
Most often you will find the DOI at the beginning of the article (look on the first page, above the title or in the header and footer).
If you’re using an academic database, you will also often find the DOI listed in the information for the article. In some cases, it may not be formatted correctly:
In this example, you would need to edit the link to get rid of “dx” and the library extension (“ezproxy.aec.talonline.ca”):
Before: http://dx.doi.org.ezproxy.aec.talonline.ca/10.1037/cpp0000189
After: http://doi.org/10.1037/cpp0000189
Note that normally we would use https instead of http.
Older Methods
In the past, DOIs were sometimes formatted differently:
http://dx.doi.org/10.9987/75098acg334
doi:10.9987/75098acg334
If you are citing the same DOI today, you’ll want to use the current format:
https://doi.org/10.9987/75098acg334
Conclusion
If you’re doubtful about the usefulness of DOIs, just take a DOI (not one from this article–they’re mostly made up) and copy it in your browser’s address bar (then press Enter). Alternatively, you can go directly to the DOI resolver at https://www.doi.org/. Knowing the DOI allows you to easily find the text it belongs to.
For more information about DOIs, please consult pp. 298-300 of the Publication Manual of the American Psychological Association (7th ed.).