LIGUN, A. A.; CHERNAYA, E. V. On extremal problems on classes of functions defined by integral moduli of continuity. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 11, p. 1499–1503, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5148. Acesso em: 14 apr. 2025.