http://www.erowid.org/library/books_online/pihkal/pihkal055.shtml (http://www.erowid.org/library/books_online/pihkal/pihkal055.shtml)
http://www.erowid.org/library/books_online/pihkal/pihkal.shtml#index (http://www.erowid.org/library/books_online/pihkal/pihkal.shtml#index)