Andrzej Jodlowski Piotr Habela Jacek Plodzien Kazimierz Subieta Extending OO Metamodels towards Dynamic Object Roles. 1032-1047 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2888&spage=1032 2003 conf/coopis/2003 CoopIS/DOA/ODBASE db/conf/coopis/coopis2003.html#JodlowskiHPS03