S. Römer, J. Mayer, F. Schweiggert, M. Maier, und T. Vollmer. Proceedings of the 25th conference on IASTED International Multi-Conference: Software Engineering, Seite 183--191. Anaheim, CA, USA, ACTA Press, (2007)
J. Van den Bergh, und K. Coninx. Proceedings of the 6th international conference on Task models and diagrams for user interface design, Seite 98--111. Berlin/Heidelberg, Springer-Verlag, (2007)