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Signal Processing 
The Scientist and Engineer's Guide to Digital Signal Processing (DSP), by S.W. Smith
Introduction to Statistical Signal Processing (R.M. Gray and L.D. Davisson)
Modern Signal Processing (Edited by D.N. Rockmore, et al) Digital Filters: An Introduction
Introduction to DSP (Digital Signal Processing) An Introduction to Signal Processing (T. O'Haver)
Wavelets and Signal Processing Signal Processing Tutorials