- Author: Rolf Porst (auth.)
- Language: German
- Year: 2000
- Author: Dr. disc. pol. Walter Spöhring (auth.)
- Language: German
- Year: 1989
- Author: Horst Jürgen Helle
- Language: German
- Year: 1977
- Author: Dipl.-Volksw. Walter Bungard Prof. Dr. Helmut E. Lück (auth.)
- Language: German
- Year: 1974
- Author: Heiner Meulemann (auth.)
- Language: German
- Year: 2001
- Author: Michael Windzio (auth.)
- Language: German
- Year: 2013
- Author: Prof. Dr. Dieter Claessens (auth.)
- Language: German
- Year: 1995
- Author: Prof. Dr. rer. pol. Heinz Sahner (auth.)
- Language: German
- Year: 1993
- Author: Dr. rer. pol. Roland Scharff (auth.)
- Language: German
- Year: 1989