Silke Kuball Gordon Hughes Evidential Volume Approach for Certification. 246-257 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2655&spage=246 2003 conf/adaEurope/2003 Ada-Europe db/conf/adaEurope/adaEurope2003.html#KuballH03