R. Cooley, B. Mobasher, and J. Srivastava. International Conference on Tools with Artificial Intelligence (ICTAI), page 558--567. IEEE, IEEE Computer Society, (1997)
S. Jespersen, T. Pedersen, and J. Thorhauge. Proceedings of the 5th ACM International Workshop on Web Information and Data Management, page 82--89. New York, NY, USA, ACM, (2003)