- Author: Gurucharan Singh Khalsa Ph.D., Yogi Bhajan Ph.D.
- Language: English
- Year: 2008
- Author: Gurucharan Singh Khalsa
- Language: English
- Year: 2007
- Author: Gurucharan Singh Khalsa
- Language: English
- Year: 2012
- Author: Yogi Bhajan Gurucharan Singh Khalsa
- Language: English
- Year: 1998