- Author: Rudolf Steiner Christopher Bamford Sabine H. Seiler
- Language: English
- Year: 1909
- Author: Rudolf Steiner Michael Lipson
- Language: English
- Year: 1995
- Author: Rudolf Steiner Catherine E. Creeger
- Language: English
- Year: 1997
- Author: Rudolf Steiner Catherine E. Creeger
- Language: English
- Year: 1997