VAKARCHUK, S. B. Jackson-type inequalities with generalized modulus of continuity and exact values of the $n$-widths of the classes of $(ψ,β)$-differential functions in $L_2$. I. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 6, p. 723–745, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1874. Acesso em: 27 apr. 2025.