MATVIICHUK, M. Yu. Common periodic trajectories of two mappings. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 7, p. 937–948, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3210. Acesso em: 5 dec. 2025.