M. Burghardt, M. Heckner, und C. Wolff. Volume 4 von Library and Information Science, Kapitel 2, Seite 19--46. Emerald Group Publishing Limited, (2012)
D. Donato, F. Bonchi, T. Chi, und Y. Maarek. Proceedings of the 19th international conference on World wide web, Seite 321--330. New York, NY, USA, ACM, (2010)
K. McNally, M. O'Mahony, B. Smyth, M. Coyle, und P. Briggs. Proceedings of the 15th international conference on Intelligent user interfaces, Seite 179--188. New York, NY, USA, ACM, (2010)