1. Newell, A.: et al. Speech Understanding Systems: Final Report of a Study Group, (American Elsevier, Amsterdam, North Holland 1971),Reprinted by, 1973
2. Flanagan, J.L.: Speech Analysis, Synthesis and Perception, (Springer, New York 1972)
3. Schafer, R.N., and Rabiner, L.R.: ‘Parametric representations of speech’, Reddy, D.R., Speech Recognition: Invited Papers of the IEEE Symposium, (Academic Press, New York 1975), p. 99–150