Guizhen Yang Michael Kifer Chang Zhao Flora-2: A Rule-Based Knowledge Representation and Inference Infrastructure for the Semantic Web. 671-688 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2888&spage=671 2003 conf/coopis/2003 CoopIS/DOA/ODBASE db/conf/coopis/coopis2003.html#YangKZ03