R. Schaefer, S. Bleul, and W. Mueller. Engineering Human Computer Interaction and Interactive Systems, volume 3425 of Lecture Notes in Computer Science, Springer Berlin Heidelberg, (2005)
S. Römer, J. Mayer, F. Schweiggert, M. Maier, and T. Vollmer. Proceedings of the 25th conference on IASTED International Multi-Conference: Software Engineering, page 183--191. Anaheim, CA, USA, ACTA Press, (2007)
R. Schäfer, S. Bleul, and W. Müller. volume 3425/2005 of Lecture Notes in Computer Science, Engineering Human Computer Interaction and Interactive Systems, page 221-223. Springer Berlin, (2005)