1. Institute of Economics & Institute of Media and Mobile Communication, Ilmenau University of Technology, Ilmenau, Germany
2. Chair for Media Economics, Media Economics, Faculty of Media, Bauhaus-University Weimar, Weimar, Germany
3. Chair for Media Economics, Faculty of Media, Bauhaus-University Weimar, Weimar, Germany
4. Economic Theory Unit, Institute of Economics, Ilmenau University of Technology, Ilmenau, Germany