K. Beyer, J. Goldstein, R. Ramakrishnan, and U. Shaft. Proceeding of the 7th International Conference on Database Theory, volume 1540 of Lecture Notes in Computer Science, page 217-235. Springer, (1999)
H. Leung, K. Chung, and S. Chan. Advances in Knowledge Discovery and Data Mining, 7th Pacific-Asia Conference, PAKDD 2003, Proceedings, volume 2637 of Lecture Notes in Computer Science, page 356-362. Springer, (2003)