1. Orthogonal Transforms for Digital Signal Processing
2. Excellent introduction to Fourier and Walsh–Fourier analysis from the engineering perspective. Discusses the fast Fourier and fast Walsh–Fourier transforms in a fair amount of detail, and FORTRAN computer subroutines for both transforms are provided
3. Excellent introductions to Walsh and related functions, also, and to the spectral decomposition of time series via the Walsh–Fourier transform from the engineering perspective. Comparisons between Walsh–Fourier and Fourier decompositions of simulated data, as well as waveform synthesis using sinusoids and Walsh functions, are discussed in detail. Provides a perspective on situations when Walsh based analysis, as opposed to trigonometric-based analysis, is relevant. The 1984 edition is essentially an updated version of the 1975 text and contains examples of many engineering applications of Walsh functions as well as a fairly up to date list of references