Javier Lacasta Javier Nogueras-Iso Pedro R. Muro-Medrano F. Javier Zarazaga-Soria Thematic Clustering of Geographic Resource Metadata Collections. 30-43 2007 W2GIS http://dx.doi.org/10.1007/978-3-540-76925-5_3 conf/w2gis/2007 db/conf/w2gis/w2gis2007.html#LacastaNMZ07