1. Buxton, B.: Sketching User Experiences: Getting the Design Right and the Right Design. Morgan Kaufmann, San Francisco (2007)
2. Hassenzahl, M., Tractinsky, N.: User experience—a research agenda. Behav Inf Technol 25(2), 91–97 (2006)
3. Lazar J.: Universal Usability: Designing Computer Interfaces for Diverse User Populations. John Wiley and Sons (2007)
4. Stephanidis, C.: Universal Access. In: HCI: Towards an Information Society for All, Proceedings of HCI International ‘2001 (the 9th International Conference on Human-Computer Interaction), New Orleans, USA, August 5-10, 2001, Volume 3, Lawrence Erlbaum (2001)
5. Empirica: Assessment of the Senior Market for ICT Progress and Developments, Bonn and Bruxells, http://ec.europa.eu/information_society/newsroom/cf/itemlongdetail.cfm?item_id=4286 . Accessed 17.01.2011 (2008)