P. Woodland, J. Odell, V. Valtchev, and S. Young. Proceedings of the 1994 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2, page 125-128. Adelaide, Australia, (April 1994)
A. Harati, J. Picone, and M. Sobel. Proceedings of the Neural Information Processing Systems Conference (NIPS), page 1–7. Lake Tahoe, Nevada, USA, (March 2013)