Y. Song, Z. Zhuang, H. Li, Q. Zhao, J. Li, W. Lee, and C. Giles. Proceedings of the 31st Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, page 515--522. New York, NY, USA, ACM, (2008)
J. Zuo, C. Tang, C. Li, C. an Yuan, and A. long Chen. Advances in Web-Age Information Management: 5th
International Conference, WAIM 2004, volume 3129 of Lecture Notes in Computer Science, page 55--64. Dalian, China, Springer, (15-17 July 2004)