- Author: Rudolf Englert, Helga Kohler-Spiegel, Norbert Mette, Elisabeth Naurath, Bernd Schröder, Friedrich Schweitzer
- Language: German
- Year: 2019
- Author: Rudolf Englert, Helga Kohler-Spiegel, Norbert Mette, Elisabeth Naurath, Bernd Schröder, Friedrich Schweitzer
- Language: German
- Year: 2019
- Author: Rudolf Englert, Helga Kohler-Spiegel, Norbert Mette, Friedrich Schweitzer, Folkert Rickers
- Language: German
- Year: 2019