I play rock and electric guitar. All my life, I only had to apply in practice barre chords, power chords, open chords and simple chords like maj, min, maj7, min7, 7, 5, sus4 etc. I know these movable chord shapes and how they are built. But I never had to play other chords like m6/9, +7b9, m7b5, 7#11 etc. and so I never learnt.
Recently, I wanted to work on all those chords, how they are built, the formulae and theories to broaden my knowledge. Couple of books that I have don't provide clear and detailed information. They are just with chord charts and notes. Searched for a better book on the internet and found exactly what I wanted.
All the chord charts and photographs of fingers on fretboard in five different voicings, notations, chord notes (C, E, G etc.), intervals (root, 3rd, 5th etc.) are clearly written. Definition and types of chords, intervals, inversions and voicing are also briefly covered. Understanding this book makes you capable of building and playing any chords on guitar.
It's affordable, handy, half the A4 size and fits in guitar case wherever you wanna go. Even for an advanced player or just a beginner, I'm sure it helps a lot as a reference book or guide.