KOSTICH, M. V. On the approximation of functions from Weyl-Nagy classes by Zygmund sums in the $L_q$ metric. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 2, p. 268–270, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4608. Acesso em: 5 dec. 2025.