A. S. Serdyuk and I. V. Sokolenko, “Approximation by Fourier sums in classes of differentiable functions with high exponents of smoothness”, MFAT, vol. 25, no. 4, pp. 381–387, Dec. 2019, Accessed: Dec. 15, 2025. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/740