L. Lee. Proceedings of the 37th annual meeting of the Association for Computational Linguistics on Computational Linguistics, page 25--32. Morristown, NJ, USA, Association for Computational Linguistics, (1999)
M. Sanderson, and W. Croft. Proceedings of the 22nd Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, SIGIR'99, page 206--213. (1999)
C. Iglesias, M. Garrijo, and J. Gonzalez. Proceedings of the 5th International Workshop on Intelligent Agents V : Agent Theories, Architectures, and Languages (ATAL-98), 1555, page 317--330. Springer-Verlag: Heidelberg, Germany, (1999)
C. Aggarwal, S. Gates, and P. Yu. KDD'1999 -- Proceedings of the Fifth ACM SIGKDD
International Conference on Knowledge Discovery and Data
Mining, page 352--356. (1999)