Underhill, E.
Mysticism
Digireads.com 2005
ISBN: 1420925016
Arthur, J.
Mushrooms and Mankind
The Book Tree, Escondido, CA 2003
ISBN: 1585091510
Underhill, E.
The Essentials of Mysticism
Cosimo Classics 2007
ISBN: 1602064008
Armstrong, K.
A History of God
Ballantine Books, New York 1994
ISBN: 0345384563
Aczel, A. D.
The Mystery of the Aleph
Washington Square Press Pocket Books, New York 2001
0743422996
Schaya, L.
The Universal Meaning of the Kabbalah
University Books, Inc. 1971
ISBN: 0042960045