Nianli Ma Yiming Yang Monica Rogati Applying CLIR Techniques to Event Tracking. 24-35 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3411&spage=24 2004 conf/airs/2004 AIRS db/conf/airs/airs2004.html#MaYR04