Cidália Costa Fonte Weldon A. Lodwick Areas of fuzzy geographical entities. 127-150 2004 18 International Journal of Geographical Information Science 2 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=1365-8816&volume=18&issue=2&spage=127 db/journals/gis/gis18.html#FonteL04