- Author: Bernd Heesen Wolfgang Gruber (auth.)
- Language: German
- Year: 2009
- Author: Bernd Heesen Wolfgang Gruber (auth.)
- Language: German
- Year: 2008
- Author: Bernd Heesen Wolfgang Gruber (auth.)
- Language: German
- Year: 2016
- Author: Bernd Heesen Wolfgang Gruber (auth.)
- Language: German
- Year: 2014
- Author: Bernd Heesen Wolfgang Gruber (auth.)
- Language: German
- Year: 2011