- Author: Valentin Tomberg
- Language: English
- Year: 2010
- Author: Anonimo (Valentin Tomberg)
- Language: Italian
- Year: 2012
- Author: Anonymous, Robert Powell, Valentin Tomberg
- Language: English
- Year: 2009
- Author: Valentin Tomberg Robert Powell
- Language: English
- Year: 2006