So I have been playing the guitar for almost half of my life now as an amateur. A year ago I jumped into gypsy jazz, or should I call it swing manouche. I was always intrigued by the way Django played his guitar especially on his improvisations. And now I am wondering if anyone here could recommend me any good books focusing more on the theory for classical guitar. I never took any lessons and I feel that I am really lacking on the theory behind it.