REPOVŠ, D.; SHARKO, V. V. $S^1$-bott functions on manifolds. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 64, n. 12, p. 1685–1698, 2012. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2691. Acesso em: 5 dec. 2025.