Kothuri Venkata Ravi Kanth Siva Ravada Efficient Processing of Large Spatial Queries Using Interior Approximations. 404-424 2001 conf/ssd/2001 SSTD http://link.springer.de/link/service/series/0558/bibs/2121/21210404.htm db/conf/ssd/sstd2001.html#KanthR01