ATINDOGBE, C.; HOUNNONKPE, R. Timelike symmetries and causality in Lorentzian manifolds. International Journal of Maps in Mathematics, [S. l.], v. 1, n. 2, p. 188–218, 2018. Disponível em: https://journalmim.com/index.php/journalMIM/article/view/30. Acesso em: 3 may. 2024.