H. Klus, D. Niebuhr, and A. Rausch. Proceedings of the International Workshop on Engineering of software services for pervasive environments (ESSPE 2007), page 21--28. Dubrovnik, Croatia, ACM, (September 2007)Electronic Proceedings.
S. Goschnick, L. Sonenberg, and S. Balbo. Human-Computer Interaction, volume 332 of IFIP Advances in Information and Communication Technology, chapter 4, Springer-Verlag, Berlin/Heidelberg/New York, (2010)