R. Kumar, J. Novak, B. Pang, und A. Tomkins. WWW '07: Proceedings of the 16th international conference on World Wide Web, Seite 629--638. New York, NY, USA, ACM, (2007)
B. Bullock, H. Lerch, A. Roßnagel, A. Hotho, und G. Stumme. Proceedings of the 11th International Conference on Knowledge Management and Knowledge Technologies, Seite 15:1--15:8. New York, NY, USA, ACM, (2011)