1. a IISI: International Institute for Socio-Informatics , Dorotheenstr. 76, 53111, Bonn, Germany
2. b Institute for Information Systems and New Media, University of Siegen , Hölderlinstr. 3, 57068, Siegen, Germany
3. c Lehrstuhl für Informatik V , RWTH Aachen, Ahornstr. 55, 52056, Aachen, Germany
4. d Fraunhofer Institute for Applied Information Technology (FhG-FIT), Schloss Birlinghoven , 53754 Sankt, Augustin, Germany