Z. Huang, X. Li, and H. Chen. JCDL '05: Proceedings of the 5th ACM/IEEE-CS joint conference on Digital libraries, page 141--142. New York, NY, USA, ACM Press, (2005)
N. Tatti, T. Mielikainen, A. Gionis, and H. Mannila. ICDM '06: Proceedings of the Sixth International Conference on Data Mining, page 603--612. Washington, DC, USA, IEEE Computer Society, (2006)