D. Widyantoro, T. Ioerger, and J. Yen. CIKM '99: Proceedings of the eighth international conference on Information and knowledge management, page 405--412. New York, NY, USA, ACM, (2-6 11 1999)
B. Mehta, and T. Hofmann. Proceedings of the 29th annual German conference on Artificial intelligence, page 244--259. Berlin, Heidelberg, Springer-Verlag, (2007)
K. Stoffel, and T. Studer. Database and Expert Systems Applications, volume 3588 of Lecture Notes in Computer Science, Springer, Berlin / Heidelberg, (2005)
D. Widyantoro, T. Ioerger, and J. Yen. CIKM '99: Proceedings of the eighth international conference on Information and knowledge management, page 405--412. New York, NY, USA, ACM Press, (November 1999)
T. Leckner, M. Koch, M. Lacher, and R. Stegmann. Proc. Intl. Conf. on Enterprise Information Systems (ICEIS2003), 4, page 259-264. Angers, Frankreich, (April 2003)