POLTAVETS, D. M. Cherry vector fields on the torus $T^2$. Methods of Functional Analysis and Topology, [S. l.], v. 2, n. 2, p. 94–98, 1996. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/16. Acesso em: 19 dec. 2025.