Sexuality, Magic, and Perversion is the name of a book by Francis King that was originally published in 1972. It was eye opening for the time because it revealed practices of sex magick that had developed over the previous century or so. It is more of a historical and theoretical book where my Modern Sex Magick is far more practical.
But the thing I'd like to point out is that although it is a good book, it still has a very moralistic sense to it. The title itself shows what is being implied, that the use of sex and magick is somehow a perversion. A recent post by Frater A.I.T. in his blog, "Heavens Within Earth," offers another view, that sex magick is fine, but that watching porn can