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DOI Update (May 2017)

Digital object identifiers (DOIs) are unique alphanumeric identifiers that are assigned to specific resources as a means of identifying and retrieving those resources. One of the main bodies that registers DOIs, Crossref, updated their approach to presenting DOIs in March to improve the security of the information. DOIs have undergone an evolution since they first started being used; originally, a DOI was presented as “doi: xxxxx”, then later “”. In the most recent update, Crossref has started presenting DOIs as “”, which ensures security while browsing (Crossref, n.d., Frequently Asked Questions section).

When using the APA Style rules to reference resources, all three versions of DOIs are acceptable, though moving forward, the new format will be displayed in the APA Style Blog (McAdoo, 2017, para. 6). To ensure consistency in references within a document, please use the same approach throughout; for example, if you’re working with an older document that displays the DOI as “doi: xxxxx” and you’d like to present the secure link, copy the alphanumeric string and insert it at the end of

For more information, please visit “DOI Display Guidelines Update (March 2017)” in the APA Style Blog, and to see more examples of references that contain DOIs, please search WriteAnswers for “DOI”.

Theresa Bell
Writing Centre manager

(Originally published in Crossroads May 30, 2017)


Crossref. (n.d.). Crossref DOI display. Retrieved from

McAdoo, T. (2017, March 1). DOI display guidelines update (March 2017) [Blog post]. Retrieved from