VAKARCHUK, S. B. Jackson-type inequalities and exact values of widths of classes of functions in the spaces $S^p , 1 ≤ p < ∞$. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 56, n. 5, p. 595–605, 2004. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3780. Acesso em: 21 dec. 2025.