. A. S. Serdyuk and I. V. . Sokolenko, “Approximation by Fourier sums in classes of Weyl – Nagy differentiable functions with high exponent of smoothness”, Ukr. Mat. Zhurn., vol. 74, no. 5, pp. 685–700, Jun. 2022, doi: 10.37863/umzh.v74i5.7136.