Ramanathan V. Guha Rob McCool Richard Fikes Contexts for the Semantic Web. 32-46 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3298&spage=32 2004 conf/semweb/2004 International Semantic Web Conference db/conf/semweb/iswc2004.html#GuhaMF04