P. Schonhofen. WI '06: Proceedings of the 2006 IEEE/WIC/ACM International Conference on Web Intelligence, page 456--462. Washington, DC, USA, IEEE Computer Society, (2006)
R. Angelova, and G. Weikum. SIGIR '06: Proceedings of the 29th annual international ACM SIGIR conference on Research and development in information retrieval, page 485--492. New York, NY, USA, ACM, (2006)