J. Teevan, C. Alvarado, M. Ackerman, and D. Karger. Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, page 415--422. New York, NY, USA, ACM, (2004)
D. Gomes, M. Costa, D. Cruz, J. Miranda, and S. Fontes. Proceedings of the 22Nd International Conference on World Wide Web, page 1059--1066. New York, NY, USA, ACM, (2013)