Ynze van Houten Jan Gerrit Schuurman Pløn Verhagen 15-23 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3115&spage=15 2004 conf/civr/2004 CIVR db/conf/civr/civr2004.html#HoutenSV04