S. Bergweiler, M. Deru, and D. Porta. ACM International Conference on Interactive Tabletops and Surfaces, page 245--246. New York, NY, USA, ACM, (2010)
D. Sonntag, M. Deru, and S. Bergweiler. Proceedings of the 2009 International Conference on Artificial Intelligence, ICAI 2009, July 13-16, 2009, Las Vegas Nevada, USA, 2 Volumes, page 974--979. (2009)