McClellan, James H., Ronald W. Schafer, and Mark A. DSP First: A Multimedia Approach. Yoder Prentice Hall, 1998.
Weaver ,W., and C. E. Shannon. The Mathematical Theory of Communication. Urbana, Illinois Press: University of Illinois Press, 1949. Republished in paperback, 1963.
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Karu, Zover. Z. Signals and Systems Made Ridiculously Simple. ZiZi Press.