A. Nguyen, and W. Wobcke. Proceedings of the 10th international conference on Intelligent user interfaces, page 137--144. New York, NY, USA, ACM, (2005)
M. Blumendorf, G. Lehmann, and S. Albayrak. Proceedings of the 2nd ACM SIGCHI symposium on Engineering interactive computing systems, page 9--18. New York, NY, USA, ACM, (2010)