5Michael S, Bidjan T. Using ontologies for advanced information access[ C]. The 3rd Int. Conference and Exhibition on The Practical Application of Knowledse Management[ C]. Manchester, UK, 2000.
6Andre asA, Ansgar B, Knut H, et al. Toward a technology for organizational memories[J]. IEEE Intelligent Systems, 1998, 13(3): 40-48.
7Yigal A, Craig A, Shen WM. Query reformulation for dynamic information integration[ J]. Intelligent Information Systems, 1996, 6(2/3): 99 - 130.
8Huh S, Moon K, Lee H. A data abstraction approach for query relaxation[J]. Information and Software Technology, 2000, 42(6):407 -418.