M. Phillips, J. Nguyen, and A. Mischke. Advances in Speech Recognition: Mobile Environments, Call Centers and Clinics, chapter 3, Springer, New York, (2010)
L. Chen, J. Hoey, C. Nugent, D. Cook, and Z. Yu. IEEE Transactions on Systems, Man, and Cybernetics, Part C: Applications and Reviews, 42 (6):
790-808(November 2012)
R. Neßelrath, and J. Alexandersson. Proceedings of the 6th IJCAI Workshop on Knowledge and Reasoning in Practical Dialogue Systems, Pasadena, CA, USA, page 46-51. (2009)