Serdyuk, A. S., and I. V. Sokolenko. “Approximation by Fourier Sums in Classes of Differentiable Functions With High Exponents of Smoothness”. Methods of Functional Analysis and Topology 25, no. 4 (December 25, 2019): 381–387. Accessed December 15, 2025. https://zen.imath.kiev.ua/index.php/mfat/article/view/740.