MAKSIMENKO, S. I. Period functions for $\mathcal{C}^0$- and $\mathcal{C}^1$-flows. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 7, p. 954–967, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2928. Acesso em: 5 dec. 2025.