Hello Edwin.
I just recently passed the PMP exam. I started my SERIOUS exam prep
about 2 months before the exam. I took and passed on 25 September
(1st try). My first order of business in my exam prep was to read the
PMBOK entirely. I had two main mistakes. I was not consistent in
reading through the PMBOK (and I read all the chapters), and I delayed
reading through the Glossary until later in my exam prep.
There are a lot of pmp exam prep materials out there, especially
through the Internet. I am not familiar with Andy Crowe's book, but I
used a couple other resources, which were very useful.
To answer your question about PMBOK, I would strongly suggest you read
through the PMBOK (4th Edition) at least once, including the Glossary.
It might also be useful to give yourself time to read and re-read
chapters, or at least parts that you did not understand. Even if you
use a prep book, that book will refer you to the PMBOK for
explanations.
Also if you take any practice exams - again for which there are many
in the world & and which is very useful to help you get a feel for the
exam (see
oliverlehman.com for some good resources) - the good
practice exams will refer to the PMBOK or other references in
explaining the correct responses.
Bottom line - PMBOK should be on the top of your list for exam prep
study.
Good luck.
Ibrahim Siddiq, PMP