DERETS, E. V. On lower bounds for the widths of classes of functions defined by integral moduli of continuity. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 3, p. 319–328, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4421. Acesso em: 27 apr. 2025.