N. Reshef, I. Guy, and M. Jacovi. Proceedings of the ACM 2009 international conference on Supporting group work, page 277--280. New York, NY, USA, ACM, (2009)
P. Katz, T. Lunze, M. Feldmann, D. Röhrborn, and A. Schill. Business Information Systems, volume 87 of Lecture Notes in Business Information Processing, Springer Berlin Heidelberg, (2011)