Natsuki Ishida Shin'ichiro Matsuo Wakaha Ogata 137-150 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2851&spage=137 2003 conf/isw/2003 ISC db/conf/isw/isc2003.html#IshidaMO03