R. del Hoyo, I. Hupont, F. Lacueva, and D. Abad\'ıa. Proceedings of the International Workshop on Affective-Aware Virtual Agents and Social Robots, page 3:1--3:4. New York, NY, USA, ACM, (2009)
B. Hu, S. Dasmahapatra, P. Lewis, and N. Shadbolt. Tools with Artificial Intelligence, 2003. Proceedings. 15th IEEE
International Conference on, page 77--82. (2003)