Published on in Vol 18 , No 6 (2016) :Jun

1 School of Computer Science and Communication , KTH Royal Institute of Technology , Stockholm , SE
2 Institute of Informatics , TH Köln - University of Applied Sciences , Gummersbach , DE
3 Department of Information Technology , Uppsala University , Uppsala , SE
4 Örebro University School of Business , Örebro University , Örebro , SE
*all authors contributed equally