K. Joo, J. Lee, I. Kim, S. Lee, and J. Lee. Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
M. Szomszor, I. Cantador, and H. Alani. Proceedings of the 19th ACM Conference on Hypertext and Hypermedia (Hypertext 2008), page 33--42. New York, NY, USA, ACM, (June 2008)