T. Prante, K. Petrovic, and R. Stenzel. page 291-302. Paderborn, Germany, Oldenbourg, München, (2004)Mensch & Computer 2004 - Allgegenwärtige Interaktion.
T. Baier, H. Weinreich, and F. Wollenweber. page 189-198. Paderborn, Germany, Oldenbourg, München, (2004)Mensch & Computer 2004 - Allgegenwärtige Interaktion.
T. Baier, and C. Kunze. page 329-342. Kluwer Academic Publishers, Dordrecht, (2004)Building the E-Service Society: E-Commerce, E-Business, and E-Government.