2A.E.Howe,D.Dreilinger.Savvy Search: A meta-search engine that learns with search engines to query.AI Maganize,1997,18(2):19~25
3A.L.Powell,J.C.French,J.P.Callan,M.E.Connell and C.L.Viles.The impact of database selection on distributed searching.In: Proceedings of 23rd Ann.Int'l ACM SIGIR Conf.Research and Development in Information Retrival,2000.232~239
4C.T.Yu,W.Meng,W.Wu and K.-L.Liu.Efficient and effective metasearch for text database incorporating linkages among documents.ACM SIGMOD,2001:187~198