M. Morris, und E. Horvitz. UIST '07: Proceedings of the 20th annual ACM symposium on User interface software and technology, Seite 3--12. New York, NY, USA, ACM, (2007)
T. Mandl. Proceedings of the 17th ACM Conference on Hypertext and Hypermedia (HT '06) Odense, Denmark, August 22nd-25th., Seite 73-84. ACM Press, (2006)