ZHYHALLO, T. V.; KHARKEVYCH, Yu. I. Approximation of (ψ, β)-differentiable functions by Poisson integrals in the uniform metric. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 61, n. 11, p. 1497–1515, 2009. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3117. Acesso em: 5 dec. 2025.