- Author: Kai Borgeest
- Language: English
- Year: 2018
- Author: Kai Borgeest
- Language: German
- Year: 2020
- Author: Kai Borgeest (auth.)
- Language: German
- Year: 2010
- Author: Kai Borgeest (auth.)
- Language: German
- Year: 2008
- Author: Kai Borgeest
- Language: English
- Year: 2018
- Author: Kai Borgeest (auth.)
- Language: German
- Year: 2014
- Author: Kai Borgeest (auth.)
- Language: German
- Year: 2010