Stepanets, O. I. “Rate of Convergence of Fourier Series on the Classes of $\overline{\psi}$-Integrals”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 8 (August 25, 1997): 1069–1113. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5102.