Alexander (better known as “Sasha”) and Ann Shulgin’s PiHKAL: A Chemical Love Story has become a foundational work in the genre and was the first book to fully impart the how-to chemistry, and convey the effects, of many of the entheogenic drugs that are currently being studied and used to heal trauma and deal with death.

https://www.amazon.com/Pihkal-Chemical-Story-Alexander-Shulgin/dp/0963009605