Publication Manual of the American Psychological Association by What does a DOI look like? 
Where do I find a DOI? Generally, on the first page of an article or the results of a database search.
What if I can't find a DOI? 
Retreives the DOI (if one exists). If you still can't find a DOI, you can use the URL for the journal's homepage in the citation. See APA DOI and URL flowchart for more info.
