STEPANETS, O. I. Approximate properties of the Zygmund method. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 4, p. 493–518, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4635. Acesso em: 6 dec. 2025.