Micah Dubinko Ravi Kumar Joseph Magnani Jasmine Novak Prabhakar Raghavan Andrew Tomkins Visualizing tags over time. 193-202 2006 conf/www/2006 WWW http://doi.acm.org/10.1145/1135777.1135810 db/conf/www/www2006.html#DubinkoKMNRT06