Rivard, G. (June 1977). "Direct fast Fourier transform of bivariate functions". IEEE Transactions on Acoustics, Speech, and Signal Processing. 25 (3): 250–252. doi:10.1109/TASSP.1977.1162951. ISSN0096-3518.
Rivard, G. (June 1977). "Direct fast Fourier transform of bivariate functions". IEEE Transactions on Acoustics, Speech, and Signal Processing. 25 (3): 250–252. doi:10.1109/TASSP.1977.1162951. ISSN0096-3518.