Theory and Application of Digital Signal Processing
This book is one of the two first classic books in DSP from the mid 1970s.
Digital Signal Processing
Schaums Outline of Digital Signal Processing, 2nd Edition (Schaum's Outlines)
The Fast Fourier Transform: An Introduction to Its Theory and Application
Discrete-Time Signal Processing (3rd Edition) (Prentice-Hall Signal Processing Series)
Applications of Digital Signal Processing