C. Cattuto, D. Benz, A. Hotho, and G. Stumme. International Semantic Web Conference, volume 5318 of Lecture Notes in Computer Science, page 615-631. Springer, (2008)
K. Tso-Sutter, L. Marinho, and L. Schmidt-Thieme. SAC '08: Proceedings of the 2008 ACM symposium on Applied computing, page 1995--1999. New York, NY, USA, ACM, (2008)