YURCHUK, I. A. Combinatorial aspects of the topological classification of functions on a circle. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 6, p. 829–836, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3199. Acesso em: 6 dec. 2025.