H. Wu, M. Zubair, and K. Maly. HYPERTEXT '06: Proceedings of the seventeenth conference on Hypertext and hypermedia, page 111--114. New York, NY, USA, ACM Press, (2006)
C. Marlow, M. Naaman, D. Boyd, and M. Davis. HYPERTEXT '06: Proceedings of the seventeenth conference on Hypertext and hypermedia, page 31--40. New York, NY, USA, ACM Press, (2006)