J. Mackinlay, R. Rao, and S. Card. Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, page 67--73. New York, NY, USA, ACM Press/Addison-Wesley Publishing Co., (1995)
F. Paternò, C. Santoro, and L. Spano. Proceedings of the 12th IFIP TC 13 International Conference on Human-Computer Interaction: Part I, page 892--905. Berlin/Heidelberg, Springer-Verlag, (2009)