Ya-Xi Chen Rodrigo Santamaría Andreas Butz Roberto Therón TagClusters: Semantic Aggregation of Collaborative Tags beyond TagClouds. 56-67 2009 Smart Graphics http://dx.doi.org/10.1007/978-3-642-02115-2_5 conf/sg/2009 db/conf/sg/sg2009.html#ChenSBT09