It's one of the original sex books and is available at most bookstores, even online. One of the nice things about this book is that it gives equal attention to the pleasures for men and women. It sounds like you think you are doing this too much. Perhaps you may be. Without knowing the frequency, it's hard to say if it is excessive or if you are feeling guilty about the rate you are doing it.
Excessive masturbation is like a drug.
It is certainly a mood altering experience. It takes you away from real contact with people. I would rather you devoted your energy with people rather than to self-stimulation. It has to do with the physical sexual maturity of the boy. Just like girls, sexual maturation in this country has been coming earlier and earlier at younger ages.