Y. Yanbe, A. Jatowt, S. Nakamura, and K. Tanaka. JCDL '07: Proceedings of the 7th ACM/IEEE-CS joint conference on Digital libraries, page 107--116. New York, NY, USA, ACM, (2007)
Y. Song, L. Zhang, and C. Giles. CIKM '08: Proceeding of the 17th ACM conference on Information and knowledge mining, page 93--102. New York, NY, USA, ACM, (2008)