H. Spada, A. Meier, N. Rummel, and S. Hauser. Proceedings of th 2005 conference on Computer support for collaborative learning: learning 2005: the next 10 years!, page 622–631. International Society of the Learning Sciences, (2005)
F. Moritz, and C. Meinel. Computer and Information Science, ACIS International Conference on, 0, page 367--372. Los Alamitos, CA, USA, IEEE Computer Society, (2010)
A. Meschtscherjakov. Proceedings of the 11th International Conference on Human-Computer Interaction with Mobile Devices and Services, page 1--1. Bonn, Germany, ACM, (2009)