SERDYUK, A. S. Approximation of Poisson Integrals by de la Vallée Poussin Sums. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 56, n. 1, p. 97–107, 2004. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3731. Acesso em: 5 dec. 2025.