Approximation of Poisson integrals by de la Vallee Poussin sums. Neliniini Kolyvannya, [S. l.], v. 13, n. 1, p. 96–99, 2010. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/552. Acesso em: 10 mar. 2026.