The following print style manual is available in Andruss Library:
Most times the DOI for an article will be listed in the database citation, like so:
or on the article itself, usually at the bottom of the page, like so:
If neither of those methods work, trying searching for the DOI on the Crossref website:
Still can't find a DOI? Then it is likely a DOI was never assigned.
Questions? Ask a librarian!