PICHUGOV, S. A. Some properties of the moduli of continuity of periodic functions in metric spaces. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 12, p. 1657–1664, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1951. Acesso em: 5 dec. 2025.