Jonathan Gemmell Maryam Ramezani Thomas Schimoler Laura Christiansen Bamshad Mobasher The impact of ambiguity and redundancy on tag recommendation in folksonomies. 45-52 2009 RecSys http://doi.acm.org/10.1145/1639714.1639724 conf/recsys/2009 db/conf/recsys/recsys2009.html#GemmellRSCM09