1. B.P. Bogert, M.J.R. Healy, J.W. Tukey: The quefrency alanysis of times series for echos: cepstrum, pseudo-autocovariance, cross-cepstrum, and saphe cracking, Proc. of the Symposium on Time Series Analysis, ed. by M. Rosenblatt (Wiley, New York 1963)
2. R.W. Schafer: Echo removal by discrete generalized linear filtering (MIT, Cambridge 1968), Ph.D. dissertation
3. A.V. Oppenheim, R.W. Schafer, T.G. Stockham Jr.: Nonlinear filtering of multiplied and convolved signals, Proc. IEEE 56(8), 1264-1291 (1968)
4. A.V. Oppenheim, R.W. Schafer, J.R. Buck: Discrete-Time Signal Processing (Upper Saddle River, Prentice-Hall 1999)
5. A.V. Oppenheim: Superposition in a Class of Nonlinear Systems (MIT, Cambridge 1964), Ph.D. dissertation, Also: MIT Research Lab. of Electronics, Cambridge, Massachusetts, Technical Report 432