CMOS

Q. Are there any books that assist in web content (APA style)?

A. I’m sure you meant to write to the APA’s Q&A and reached us by mistake—but we aren’t inclined to be petty. Maybe Chicago style isn’t right for your content. So for fifteen bucks, you can buy Charles Lipson’s Cite Right: A Quick Guide to Citation Styles—MLA, APA, Chicago, the Sciences, Professions, and More. The basics of APA style are also available online; just type “APA style” into your search engine.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]