S. Dumais, and W. Jones. CHI '85: Proceedings of the SIGCHI conference on Human factors in computing systems, page 127--130. New York, NY, USA, ACM, (1985)
J. Thom-Santelli, M. Muller, and D. Millen. CHI '08: Proceeding of the twenty-sixth annual SIGCHI conference on Human factors in computing systems, page 1041--1044. New York, NY, USA, ACM, (2008)