db/conf/cikm/YuOE99.html Byunggu Yu Ratko Orlandic Martha W. Evens Simple QSF-Trees: An Efficient and Scalable Spatial Access Method. 5-14 CIKM1999/P005.pdf 1999 conf/cikm/99 CIKM http://doi.acm.org/10.1145/319950.319953 db/conf/cikm/cikm99.html#YuOE99