OVSII, E. Yu.; SERDYUK, A. S. Approximation of the classes $C_{β}^{ψ} H_{ω}$ by generalized Zygmund sums. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 61, n. 4, p. 524–537, 2009. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3037. Acesso em: 9 dec. 2025.