M. Grahl, A. Hotho, и G. Stumme. 7th International Conference on Knowledge Management (I-KNOW '07), стр. 356-364. Graz, Austria, Know-Center, (сентября 2007)
D. Millen, J. Feinberg, и B. Kerr. CHI '06: Proceedings of the SIGCHI conference on Human Factors in computing systems, стр. 111--120. New York, NY, USA, ACM Press, (2006)