For works without DOIs from most academic research databases:

• Do not include a URL or database information in the reference because these works are widely available.
• The reference should be the same as the reference for a print version of the work.

Taken from the APA Style website

See our Dealing with an Absent DOI Library Guide for more information. 

Lesson 5 on Academic Writer's Journal Article Reference Quick Guide gives a brief DOI overview.