For what it's worth, the supplemental book I chose was the primary study source for me (I used Rita's book). I NEVER read the PMBOK cover-to-cover. For me, it is mind numbing. I DID use it as a reference frequently to resolve questions and I would skim over it, particularly the process flow diagrams with inputs/outputs.
To jump on John's comment, I used flashcards (loaded on my smart phone) so I could study terms wherever I was and had a few minutes. It DID help me.
Good luck!
Tracy