1. Bangor, A., Kortum, P., Miller, J.: Determining what individual SUS scores mean: adding an adjective rating scale. J. Usability Stud. 4(3), 114–123 (2009)
2. Allen, R.B.: Cognitive factors in the use of menus and trees: An experiment. IEEE J. Sel. Areas Commun. 1, 333–336 (1983)
3. Frøkjær, E., Hertzum, M., Hornbæk, K.: Measuring usability: Are effectiveness, efficiency, and satisfaction really correlated?. In: Proceedings of the ACM CHI 2000, pp. 345–352 (2000)
4. The de facto industry standard evaluation questionnaire for assessing quality of use of software by end users.
http://sumi.ucc.ie/
5. Information Technology Research and Standardization Center (INSTAC), JSA. The standardization of 4-direction key interaction of mobile information devices (2010)