Jim Macklin wrote:
The best single book in my opinion is William K. Kershner's
THE FLIGHT INSTRUCTOR"S MANUAL, now published by ASA
http://www.asa2fly.com/
Also all the FAA books can be downloaded free from the FAA
http://www.faa.gov/pilots/training/
http://www.faa.gov/library/manuals/aviation/
Instructors handbook
http://www.faa.gov/library/manuals/a...A-H-8083-9.pdf

I concur with Jim's advice. But basically, get a printed copy of
the PTS and the CFI Oral test quide (from ASA) and use those as a
basis for what you need to know. The back of the Oral Test study
guide also has the wording of all of the various endorsements you
would need and handy to have.