D. Sonntag, and P. Heim. KI 2007: Advances in Artificial Intelligence, volume 4667 of Lecture Notes in Artificial Intelligence, Springer, Berlin, (2007)
R. Engel, and D. Sonntag. KI 2007: Advances in Artificial Intelligence, volume 4667 of Lecture Notes in Artificial Intelligence, Springer, Berlin, (2007)