HRABOVA, U. Z.; SERDYUK, A. S. Order Estimates for the Best Approximations and Approximations by Fourier Sums of the Classes of (ψ, β)-Differential Functions. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 65, n. 9, p. 1186–1197, 2013. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2500. Acesso em: 11 apr. 2025.