H. Giles, E. Manavoglu, H. Zha, Z. Zhang, and E. Fox. In JCDL ’03: Proceedings of the 3rd ACM/IEEE-CS Joint Conference on Digital Libraries, page 37--48. (2003)
U. Lee, Z. Liu, and J. Cho. WWW '05: Proceedings of the 14th International World Wide Web Conference, page 391--400. New York, NY, USA, ACM Press, (2005)