USENKO, E. G. Criteria for the coincidence of the kernel of a function with the kernels of its Riesz and Abel integral means. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 12, p. 1712–1714, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4792. Acesso em: 27 apr. 2025.