B. Hu, S. Dasmahapatra, P. Lewis, and N. Shadbolt. Tools with Artificial Intelligence, 2003. Proceedings. 15th IEEE
International Conference on, page 77--82. (2003)
N. Fuhr, and P. Muller. 10th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, page 13-18. New Orleans, Louisiana, United States, ACM Press, (1987)
E. Efthimiadis. SIGIR '93: Proceedings of the 16th annual international ACM SIGIR conference on Research and development in information retrieval, page 146--159. New York, NY, USA, ACM, (1993)