- Author: Ralf Grüttemeier, Klaus Beekman, Ben Rebel
- Language: English
- Year: 2013
- Author: Ralf Grüttemeier (editor), Janka Wagner (editor), Haimo Stiemer (editor)
- Language: German
- Year: 2020
- Author: Ralf Grüttemeier
- Language: English
- Year: 2022
- Author: Ralf Grüttemeier
- Language: English
- Year: 2022
- Author: Ralf Grüttemeier (editor)
- Language: English
- Year: 2016
- Author: Ralf Grüttemeier
- Language: English
- Year: 2016
- Author: Hubert van den Berg Ralf Grüttemeier (eds.)
- Language: German
- Year: 1998
- Author: Ralf Grüttemeier (auth.)
- Language: German
- Year: 1995
- Author: Ralf Grüttemeier Maria-Theresia Leuker (eds.)
- Language: German
- Year: 2006