APA (American Psychological Association) Style is widely used in the social sciences, business, and some of the life sciences. APA Style uses brief in-text citations in the text that refer to an alphabetical list of references appearing the end of the work.
Disciplines using APA Style include Business, Communication, Education, and Psychology.
A DOI is a unique, permanent locator for online materials.They are usually found at the top of an article or with the other citation information -- look for the letters "doi" followed by an alphanumeric sequence beginning with 10. Many older articles may not have a DOI.