S. Yardi, S. Golder, and M. Brzozowski. CHI '09: Proceedings of the 27th international conference on Human factors in computing systems, page 2071--2080. New York, NY, USA, ACM, (2009)
A. Stocker, K. Tochtermann, and N. Krasser. WM2009: 5th Conf. on Professional Knowledge Management, page 560-572. Bonn, Gesellschaft für Informatik, (2009)