George W. Furnas Caterina Fake Luis von Ahn Joshua Schachter Scott A. Golder Kevin Fox Marc Davis Cameron Marlow Mor Naaman Why do tagging systems work? 36-39 2006 conf/chi/2006a CHI Extended Abstracts http://doi.acm.org/10.1145/1125451.1125462 db/conf/chi/chi2006a.html#FurnasFASGFDMN06