Yu-Ling Hsueh Roger Zimmermann Wei-Shinn Ku Adaptive Safe Regions for Continuous Spatial Queries over Moving Objects. 71-76 2009 DASFAA http://dx.doi.org/10.1007/978-3-642-00887-0_7 conf/dasfaa/2009 db/conf/dasfaa/dasfaa2009.html#HsuehZK09