ZHYHALLO, T. V.; KHARKEVYCH, Yu. I. Approximation of $(\psi, \beta)$-Differentiable Functions Defined on the Real Axis by Abel-Poisson Operators. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 57, n. 8, p. 1097 – 1111, 2005. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3667. Acesso em: 5 dec. 2025.