R. Nesselrath, and D. Porta. Proceedings of the 7th IJCAI Workshop on Knowledge and Reasoning in Practical Dialogue Systems (KRPDS-11), page 37-47. (July 2011)
D. Rosca, S. Greenspan, M. Feblowitz, and C. Wild. Requirements Engineering, 1997., Proceedings of the Third IEEE International Symposium on, (January 1997)