Robert Jäschke Folke Eisterlehner Andreas Hotho Gerd Stumme Testing and evaluating tag recommenders in a live system. 369-372 2009 RecSys http://doi.acm.org/10.1145/1639714.1639790 conf/recsys/2009 db/conf/recsys/recsys2009.html#JaschkeEHS09