1. H.C. Andrews, Computer Techniques in Image Processing, Academic Press, New York, 1970.
2. H.C. Andrews, “Two Dimensional Transforms,” in Topics in Applied Physics: Picture Processing and Digital Filtering, Vol. 6, T.S. Huang, ed., Springer-Verlag, New York, 1975.
3. R. Gellman, Introduction to Matrix Analysis, McGraw-Hill, New York, 1960.
4. H.C. Andrews and K. Caspari, “A Generalized Technique for Spectral Analysis,” IEEE Transactions on Computers, Vol. C-19, No. 1, January 1970, pp. 16–25.
5. J.W. Cooley and J.W. Tukey, “An Algorithm for the Machine Calculation of Complex Fourier Series,” Math. Computation, Vol. 19, April 1965, pp. 297–301.