A rather good book about mastering the six string: Learn to Play Guitarrby Gareth Evans discusses all the basics and is aimed at beginners and intermediate players. The author pays attention to detail, describing lay-out of the instrument, the various methods of musical notation, basic chords, tuning and replacing the strings (a must before you hit the big time and have a pet guitar tech taking care of that).
It is a good mix of musical theory and hands-on training examples. The audio samples come in two versions, with and without the guitar, enabling the student to play over the backing track. O special interest are the stretching exercises. RSI is a bitch an by following the instructions the dreaded carpal tunnel syndrome can be avoided.
The book is published by Intuition Publications as a large scale paperback and can be bought from various retailers trough the author's website. The eBook version is free.