- Author: Gerhard Raab, Alexander Unger, Fritz Unger
- Language: German
- Year: 2022
- Author: Gerhard Raab Alexander Unger Fritz Unger
- Language: German
- Year: 2018
- Author: Gerhard Raab Alexander Unger Fritz Unger (auth.)
- Language: German
- Year: 2016
- Author: Gerhard Raab Alexander Unger Fritz Unger (auth.)
- Language: German
- Year: 2009