Peter Fröhlich Zaijun Hu Manfred Schoelzke Using UML for Information Modeling in Industrial Systems with Multiple Hierarchies. 63-72 2002 conf/uml/2002 UML http://link.springer.de/link/service/series/0558/bibs/2460/24600063.htm db/conf/uml/uml2002.html#FrohlichHS02