H. Halpin, V. Robu, and H. Shepherd. WWW '07: Proceedings of the 16th international conference on World Wide Web, page 211--220. New York, NY, USA, ACM, (2007)
M. Morris, and E. Horvitz. Proceedings of the 20th annual ACM symposium on User interface software and technology, page 3--12. New York, NY, USA, ACM, (2007)
M. Morris. Proceeding of the twenty-sixth annual SIGCHI conference on Human factors in computing systems, page 1657--1660. New York, NY, USA, ACM, (2008)