Oliver Berthold Andreas Pfitzmann Ronny Standtke The Disadvantages of Free MIX Routes and how to Overcome Them. 30-45 2000 conf/diau/2000 Workshop on Design Issues in Anonymity and Unobservability http://link.springer.de/link/service/series/0558/bibs/2009/20090030.htm db/conf/diau/diau2000.html#BertholdPS00