The Art of Classical Guitar Playing by Charles Duncan 132 pages $21.95
Published almost 25 years ago, I bought this when I first got interested in Classical Guitar, it covers the subject of playing well completely and is therefore still in print.
The chapters are:
The Principal of Functioning Tension
The Left Hand
Right Hand Position
Nail Filing
Articulation
Coordination and Velocity
Expressive Devices
The Art of Classical Guitar Playing
Expressive Nuances-Segovia's example