APA citations contain the following information:
A DOI is a digital object identifier and it’s associated with electronic content, most often academic journal articles. It is commonly placed in the top header or bottom footer of an article. If no DOI is listed, you can search the CrossRef website to try to find it.
The APA Style website explains when to use a DOI versus a website address. Here are some of the basic rules:
For ebooks and online periodical articles found on the web:
For online periodical articles found through a library subscription database: