J. Yamagishi, T. Nose, H. Zen, T. Toda, and K. Tokuda. Proceedings of the 2008 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), page 3957-3960. Las Vegas, NV, USA, (March 2008)
S. Bozza, and A. O'Hagan. Between Data Science and Applied Data Analysis: Proceedings of the 26th Annual Conference of the Gesellschaft Fűr Klassifikation Ev, 26, page 165. University of Mannheim, Springer Verlag, (2003)