Yasushi Sakurai Masatoshi Yoshikawa Shunsuke Uemura Haruhiko Kojima Spatial indexing of high-dimensional data based on relative approximation. 93-108 2002 11 VLDB J. 2 http://link.springer.de/link/service/journals/00778/bibs/2011002/20110093.htm db/journals/vldb/vldb11.html#SakuraiYUK02