Burova, A. Y., and V. V. Kabakov. “‘Unerroric’ of Multistage Discrete Fourier Transform of Digital Signal Without Arithmetic Operations of Multiplication”. Amazonia Investiga, vol. 9, no. 25, Jan. 2020, pp. 429-37, https://amazoniainvestiga.info/index.php/amazonia/article/view/1092.