S. Auer, and J. Lehmann. The Semantic Web: Research and Applications, 4th European Semantic Web Conference, ESWC 2007, Innsbruck, Austria, volume 4519 of Lecture Notes in Computer Science, Springer, Berlin, (2007)
D. Sonntag, and P. Heim. KI 2007: Advances in Artificial Intelligence, volume 4667 of Lecture Notes in Artificial Intelligence, Springer, Berlin, (2007)