J. Luxenburger, S. Elbassuoni, and G. Weikum. CIKM '08: Proceeding of the 17th ACM conference on Information and knowledge management, page 689--698. New York, NY, USA, ACM, (2008)
Y. Xu, K. Wang, B. Zhang, and Z. Chen. WWW '07: Proceedings of the 16th international conference on World Wide Web, page 591--600. New York, NY, USA, ACM, (2007)