title: a pictorial query language for querying geographic databases using positional and olap operators sigmod record 2002. authors: elaheh pourabbas , maurizio rafanelli. venue: nan. year: nan
title: a pictorial query language for querying geographic databases using positional and olap operators elaheh pourabbas , maurizio rafanelli 2002. authors: nan. venue: acm sigmod record. year: nan