- Author: Christa Drees-Behrens, Matthias Kirspel, Andreas Schmidt, Helmut Schwanke
- Language: German
- Year: 2007
- Author: Christa Drees-Behrens, Andreas Schmidt
- Language: German
- Year: 2010
- Author: Christa Drees-Behrens, Andreas Schmidt
- Language: German
- Year: 2010