http://q3o3hdjbf6vwxdnpskyhxw7w7rnmnfhz2szbuala4q24x6csbp7adiad.onion/guides/the-drug-users-bible
In a nutshell, it’s a harm reduction reference tome. From Amazon: “Over a 12 year period the author of this book self-administered over 180 psychoactive substances; both chemicals and plants. For each he recorded the life-sensitive safety data, including the anticipated onset times, the common threshold doses, the routes of administration, and the expected duration of the experience.