
- Author: Professor Dr. Walter Frenz (auth.)
- Language: German
- Year: 2008

- Author: Walter Frenz (auth.)
- Language: German
- Year: 2012

- Author: Professor Dr. Dirk Looschelders (auth.)
- Language: German
- Year: 2004

- Author: Professor Dr. Walter Frenz (auth.)
- Language: German
- Year: 2005

- Author: Dr. Thomas Wilrich (auth.)
- Language: German
- Year: 2004

- Author: Professor Dr. Walter Frenz (auth.)
- Language: German
- Year: 2008