Tad Hogg Kristina Lerman Social Dynamics of Digg. 2010 ICWSM http://www.aaai.org/ocs/index.php/ICWSM/ICWSM10/paper/view/1470 conf/icwsm/2010 db/conf/icwsm/icwsm2010.html#HoggL10