RUKASOV, V. I.; CHAICHENKO, S. O. Approximation of the Classes $C^{{\bar \psi }} H_{\omega }$ by de la Vallée-Poussin Sums. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 54, n. 5, p. 681–691, 2002. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4107. Acesso em: 6 dec. 2025.