HOFER, H.; WYSOCKI, K.; ZEHNDER, E. Unknotted periodic orbits for Reeb flows on the three-sphere. Topological Methods in Nonlinear Analysis, [S. l.], v. 7, n. 2, p. 219–244, 1996. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1996.010. Acesso em: 22 jul. 2024.