LEONCHIK, E. Yu. On One Inequality in Approximation Theory. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 55, n. 11, p. 1580–1585, 2003. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4026. Acesso em: 11 apr. 2025.