ronald.frank@gfk-verein.org
matthias.unfried@gfk-verein.org
regina.schreder@gfk-verein.org
anja.dieckmann@gfk-verein.org
© 2016 Ronald Frank, Matthias Unfried, Regina Schreder, Anja Dieckmann, published by Nuremberg Institute for Market DecisionsThis work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.