Compare Figure 1 in Townsend, W. J.; Thornton, M. A. "Walsh Spectrum Computations Using Cayley Graphs". CiteSeerX10.1.1.74.8029. {{cite journal}}: Cite journal requires |journal= (help)
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Kunz, H.O. (1979). "On the Equivalence Between One-Dimensional Discrete Walsh–Hadamard and Multidimensional Discrete Fourier Transforms". IEEE Transactions on Computers. 28 (3): 267–8. doi:10.1109/TC.1979.1675334. S2CID206621901.