Asunción Gómez-Pérez Rafael González-Cabero Manuel Lama Development of Semantic Web Services at the Knowledge Level. 72-86 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3250&spage=72 2004 conf/ecows/2004 ECOWS db/conf/ecows/ecows2004.html#Gomez-PerezGL04