Kazem Taghva Julie Borsack Thomas A. Nartker Allen Condit The role of manually-assigned keywords in query expansion. 441-458 2004 40 Inf. Process. Manage. 3 http://dx.doi.org/10.1016/j.ipm.2003.12.005 db/journals/ipm/ipm40.html#TaghvaBNC04