Magnus Carlsson Johan Nordlander Dick Kieburtz The Semantic Layers of Timber. 339-356 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2895&spage=339 2003 conf/aplas/2003 APLAS db/conf/aplas/aplas2003.html#CarlssonNK03