BORZDYKO, V. I. On the smoothness of conjugation of circle diffeomorphisms with rigid rotations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 3, p. 283–292, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3157. Acesso em: 5 dec. 2025.