- Author: Christian Ullrich
- Language: English
- Year: 1990
- Author: Christian Ullrich (auth.)
- Language: German
- Year: 2005
- Author: Christian Ullrich
- Language: English
- Year: 1990
- Author: Christian Ullrich (auth.)
- Language: German
- Year: 2004
- Author: Christian Ullrich Jürgen Wolff von Gudenberg
- Language: English
- Year: 1989
- Author: Christian Ullrich (auth.)
- Language: English
- Year: 2009