Francisco Echarte José Javier Astrain Alberto Córdoba Jesús E. Villadangos Improving folksonomies quality by syntactic tag variations grouping. 1226-1230 2009 SAC http://doi.acm.org/10.1145/1529282.1529559 conf/sac/2009 db/conf/sac/sac2009.html#EcharteACV09