Leonardo Guerreiro Azevedo Geraldo Zimbrão Jano Moreira de Souza Ralf Hartmut Güting Estimating the Overlapping Area of Polygon Join. 91-108 2005 conf/ssd/2005 SSTD http://dx.doi.org/10.1007/11535331_6 db/conf/ssd/sstd2005.html#AzevedoZSG05