1. (1992). Incremental relevance feedback. Proceedings of the 15th Annual International Conference on Research and Development in Information Retrieval (ACM SIGIR'92) (pp. 11-22), Copenhagen: ACM.
2. (1996). Incremental relevance feedback for information filtering. Proceedings of the 19th Annual International Conference on Research and Development in Information Retrieval (ACM SIGIR'96) (pp. 270-278), Zurich: ACM.
3. American Society for Information Science and Technology (ASIST). (1999). ASIS Thesaurus, 2nd edition [On-line]. Available: www.asis.org/Publications/Thesaurus/asis_thesaurus.html
4. Association for Computing Machinery (ACM). (1997). ACM Computing Classification System [On-line]. Available: http://www.acm.org/class/1991