P. Chirita, S. Costache, W. Nejdl, and S. Handschuh. WWW '07: Proceedings of the 16th International Conference on World Wide Web, page 845--854. New York, NY, USA, ACM, (2007)
K. Bollacker, C. Evans, P. Paritosh, T. Sturge, and J. Taylor. SIGMOD '08: Proceedings of the 2008 ACM SIGMOD international conference on Management of data, page 1247--1250. New York, NY, USA, ACM, (2008)
S. Braun, A. Schmidt, A. Walter, and V. Zacharias. Good Tags and Bad Tags - Social Tagging in der Wissensorganisation, volume 47 of Medien in der Wissenschaft, Waxmann, (2008)