I have always enjoyed reading material by Glen D. Zediker as he does a good job of presenting his material and backing up what he has to say be it with his personal experience or well documented facts. His now old book
The Competitive AR 15, first printing July 2008 The book is extremely well written and a wealth of knowledge for working on match service rifles AR 15. I also got a lot from his article
Reloading for the Match M 14.
As to cam over he again does a good job of explaining what is going on and press linkage as well as why he sees it as a bad idea.
Ron