ABDULLAYEV, F. G.; KHARKEVYCH, Yu. I. Approximation of the classes $C^{\psi}_{\beta}H^{\alpha}$ by biharmonic Poisson integrals. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 72, n. 1, p. 20–35, 2020. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1007. Acesso em: 5 dec. 2025.