Elizeu Santos-Neto David Condon Nazareno Andrade Adriana Iamnitchi Matei Ripeanu Individual and social behavior in tagging systems. 183-192 2009 Hypertext http://doi.acm.org/10.1145/1557914.1557947 conf/ht/2009 db/conf/ht/ht2009.html#Santos-NetoCAIR09