- Author: Hans-Jürgen Schönig
- Language: English
- Year: 2020
- Author: Hans-Jürgen Schönig
- Language: English
- Year: 2020
- Author: Hans-Jürgen Schönig
- Language: english
- Year: 2018
- Author: Hans-Jürgen Schönig
- Language: english
- Year: 2014
- Author: Zoltan Böszörmenyi Hans-Jürgen Schönig
- Language: English
- Year: 2013
- Author: Zoltan Böszörmenyi Hans-Jürgen Schönig
- Language: English
- Year: 2013