- Author: Christina Weidmann Ralf Kohlhepp
- Language: German
- Year: 2020
- Author: Christina Weidmann Ralf Kohlhepp (auth.)
- Language: German
- Year: 2014
- Author: Christina Weidmann Ralf Kohlhepp (auth.)
- Language: German
- Year: 2009
- Author: Christina Weidmann Ralf Kohlhepp
- Language: German
- Year: 2011