- Author: Donald Voet, Juudith G. Voet, Charlotte W. Pratt, Annete G. Beck-Sickinger, Ulrich Hahn, Bärbel Häcker, Otmar Asperger, Regula von Eggelkraut-Gottanka, Norman Koglin, Ulrike Krauss, Michael Langer, Maria Ludewig, Michael Richter
- Language: German
- Year: 2010