I recently started researching Demons of the Flesh, The Complete Guide to Left Hand Path Sex Magic written by Zeena Schreck (formally Zeena LaVey) and Nikolas Schreck. Hardened (no pun intended) and jaded by the LaVey Satanism I had read in the past, I wondered just how good is this book going to be? I looked it up on Amazon and saw that it was actually 400 pages long, but found it out of print with used copies selling for $248 ! So I googled the PDF and found it for free! (click on the title above for the link).
I found the book to actually be a good primer on Eastern and Western Tantras, from Vama Marga to Crowley etc. They definitely did their research, I recommend it as a good read. And at the end they got into their own twist on the subject which I did find “educational”. Zeena has evolved over the decades and is now a follower of the Karma Kagyu lineage of Tibetan Buddhism, and here is her official website. Enjoy!