The Ultimate Scale Book is something in between a reference book and a guitar method. It builds gradually, like a method, with each scale shown as a variant (or extension) of the previous scales. 
 
Includes:
What are scales?
How to learn scales
Fingering guidelines
Scale construction
Fretboard diagrams for each scale
Major pentatonic scale
Minor penatonic scale
Blues scale
Major & minor blues scales
Diatonic major and minor scales
The modes of diatonic major/minor
Harmonic and melodic minor scales
Phrygian-dominant scale
The modes of jazz minor 
Chromatic scale
Whole-tone scale
Diminished scales
Plus ethnic and exotic scales