• International Trepanation Advocacy Group (ITAG)

• The Foundation to Further Consciousness Gives information about various techniques of expanding consciousness and does research into the physiology underlying it.

• The International Trepanation Advocacy Group Information on trepanation, the art of drilling holes into people's skulls.

• Trepanation Guide An indepth source of information on medical and historical aspects of this ancient surgical procedure. Includes references and citations as well and advanced reading suggestions.

• Trepanation Trust provides scientific information, images, and articles about the practice of trepanation, including people who've done it themselves