V. L. . Grona, “Uniform convergence of the Fourier spherical sums differentiated by the function”, Ukr. Mat. Zhurn., vol. 43, no. 1, pp. 47–53, Jan. 1991, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/9304