Ariel Escribano Leticia I. Gómez Bart Kuijpers Alejandro A. Vaisman Piet: a GIS-OLAP implementation. 73-80 2007 conf/dolap/2007 DOLAP http://doi.acm.org/10.1145/1317331.1317345 db/conf/dolap/dolap2007.html#EscribanoGKV07