STEPANETS, O. I. Approximation Characteristics of Spaces $S_\phi ^p$. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 53, n. 3, p. 392–416, 2001. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4261. Acesso em: 5 dec. 2025.