A. Averbakh, D. Krause, and D. Skoutas. The Semantic Web -- ISWC 2009: 8th International Semantic Web Conference, Chantilly, VA, USA, volume 5823 of Lecture Notes in Computer Science, Springer, Berlin, (2009)
D. Sonntag, and P. Heim. KI 2007: Advances in Artificial Intelligence, volume 4667 of Lecture Notes in Artificial Intelligence, Springer, Berlin, (2007)