For information on how to cite sources in APA style, see the WMU Libraries' guide:
Citing Sources Guide - APA 7th edition Style Guide
This is the official style manual of the American Psychological Association. Chapters 8, 9, and 10 explain how to cite sources in APA style.
These books books below are a sample of materials that will help you use and interpret the writing style described in the Publication Manual of the American Psychological Association.