M. Beetz, M. Buss, and D. Wollherr. KI 2007: Advances in Artificial Intelligence, volume 4667 of Lecture Notes in Artificial Intelligence, Springer, Berlin, (2007)
M. Huber, J. Leimeister, and H. Krcmar. Workshop-Proceedings der Tagung Mensch & Computer 2009 - Grenzenlos frei!?, page 42-47. Berlin, Logos, (September 2009)ISBN: 978-3-8325-2181-3.