Antonio Corral Joaquín Cañadas Michael Vassilakopoulos Processing Distance-Based Queries in Multidimensional Data Spaces Using R-trees. 1-18 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2563&spage=1 2001 conf/pci/2001 Panhellenic Conference on Informatics db/conf/pci/pci2001.html#CorralCV01