- Author: Andrei Znamenski
- Language: English
- Year: 2011
- Author: John Amodeo PhD
- Language: English
- Year: 2013
- Author: John Amodeo PhD
- Language: English
- Year: 2013
- Author: Fred Alan Wolf
- Language: English
- Year: 2004
- Author: Caitlin Matthews
- Language: English
- Year: 2001
- Author: Stephan A. Hoeller
- Language: English
- Year: 2002
- Author: Huston Smith
- Language: English
- Year: 2003
- Author: Dora van Gelder Kunz
- Language: English
- Year: 1999
- Author: Lachman Gary
- Language: English
- Year: 2006
- Author: Georg Feuerstein Subhash Kak and David Frawley.
- Language: English
- Year: 2011