O. Nov, M. Naaman, and C. Ye. CHI '08: Proceeding of the twenty-sixth annual SIGCHI conference on Human factors in computing systems, page 1097--1100. New York, NY, USA, ACM, (2008)
S. Lee, D. Son, and S. Han. SIGDOC '07: Proceedings of the 25th annual ACM international conference on Design of communication, page 189--195. New York, NY, USA, ACM, (2007)