George Danezis Andrei Serjantov Statistical Disclosure or Intersection Attacks on Anonymity Systems. 293-308 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3200&spage=293 2004 conf/ih/2004 Information Hiding db/conf/ih/ih2004.html#DanezisS04