These are some related sites of interest:

The DuVersity The program of the DuVersity includes both research and education. It sets up dialogue groups, gives courses in corresponding and affiliated methods and organizes seminar-dialogues on wide-ranging themes. It furthers research into methods of thinking, inter-disciplinary studies and cross-cultural communication.

The Center for Self-Organizing Leadership - A holistic approach to organizational transformation. This is Richard Knowles site where he describes using the Process Enneagram©, the consulting services that he offers, and the two books that he has written.

Bennett Books Bennett Books has for many years played a significant role in keeping most of J. G. Bennett's major works in print. They also carry a significant number of other 4th Way books, recordings and music.

Wikipedia This links to the Wikipedia article on Systematics (which currently could use some additional material).

SYSTEMATICS A NEW TECHNIQUE IN THINKING This is a short but comprehensive article on Systematics from the monad to the duodecad  -  Anthony Blake.