O. Stock, and M. Zancanaro. the International CLASS Workshop on Natural Intelligent and Effective Interaction in Multimodal Dialogue Systems, Copenhagen, Denmark,, (28-29 June 2002)
P. Hasle. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), volume 4068 of Lecture Notes in Computer Science, page 2-21. Springer, (2006)