Fernando Ferri Anna Formica Patrizia Grifoni Maurizio Rafanelli Query Approximation by Semantic Similarity in GeoPQL. 1670-1680 2006 conf/otm/2006-w2 OTM Workshops (2) http://dx.doi.org/10.1007/11915072_73 db/conf/otm/otm2006-w2.html#FerriFGR06