EL-SABAA, F.M.; HOSNY, M.; ZAKRIA, S.K. Bifurcations of Liouville tori of generalized two-fixed center problem. Italian Journal of Pure and Applied Mathematics, [S. l.], v. 43, p. 331–352, 2020. Disponível em: https://journals.uniurb.it/index.php/ijpam/article/view/7336. Acesso em: 6 nov. 2026.