There is a new e-book on realtimepublishers called
The ExamPrep Guide™ to Security Certifications.
At the moment only the first chapter is on line but the rest should follow soon.

realtime publishers

I havent read the chapter yet but if it is of the same level as their other books then it should be very usefull to anyone looking to pass the exams. best thing is all the books are free on the site you just have to register. I have been useing the site as a referance and find their books to be clear well written and easily as good as any book you can buy on similar subjects.