S. Banerjee, K. Ramanathan, and A. Gupta. SIGIR '07: Proceedings of the 30th annual international ACM SIGIR conference on Research and development in information retrieval, page 787--788. New York, NY, USA, ACM, (2007)
M. Balcan, A. Blum, and A. Gupta. SODA '09: Proceedings of the Nineteenth Annual ACM -SIAM Symposium on Discrete Algorithms, page 1068--1077. Philadelphia, PA, USA, Society for Industrial and Applied Mathematics, (2009)
S. Banerjee, K. Ramanathan, and A. Gupta. SIRIR '07: Proceedings of the 30th annual international ACM SIGIR conference on Research and development in information retrieval, page 787--788. New York, NY, USA, ACM Press, (2007)