R. Jäschke, A. Hotho, C. Schmitz, and G. Stumme. Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007), volume 4604 of Lecture Notes in Artificial Intelligence, page 283--295. Berlin/Heidelberg, Springer-Verlag, (July 2007)
Y. Ahn, S. Han, H. Kwak, S. Moon, and H. Jeong. Proceedings of the 16th International Conference on World Wide Web, page 835--844. New York, NY, USA, ACM, (2007)
H. Kim, S. Hwang, and H. Kim. SAC '07: Proceedings of the 2007 ACM symposium on Applied computing, page 1340--1345. New York, NY, USA, ACM Press, (2007)