Secrets of Western Sex Magic: Magical Energy & Gnostic Trance, by Frater U.: D.:
Llewellyn Worldwide, 1567187064, 2001
Well worth picking up. Frater U.D. avoids being pretentious and expresses the concepts behind sex magic in a clear and coherent manner.
I particularly liked the exercises he included, which he made very accessible. His use of references gives him another bonus in my book.
I also liked that he presented sections of sex magic for people who aren’t heterosexual. It’s still relatively rare to see books that offer that for people who choose to live a different life