Michael S. Lew Dionysius P. Huijsmans Dee Denteneer Optimal Keys for Image Database Indexing. 148-155 1997 conf/iciap/1997-2 ICIAP (2) db/conf/iciap/iciap1997-2.html#LewHD97 http://dx.doi.org/10.1007/3-540-63508-4_117