- Author: Volkhard Wels
- Language: German
- Year: 2013
- Author: William P. Weaver (editor), Stefan Strohm (editor), Volkhard Wels (editor)
- Language: German
- Year: 2017
- Author: Volkhard Wels
- Language: German
- Year: 2009
- Author: Volkhard Wels
- Language: German
- Year: 2009
- Author: Volkhard Wels
- Language: German
- Year: 2009