O. I. Stepanets, “Rate of convergence of Fourier series on the classes of $\overline{\psi}$-integrals”, Ukr. Mat. Zhurn., vol. 49, no. 8, pp. 1069–1113, Aug. 1997, Accessed: Apr. 09, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5102