PADMAVALLY, K. A Poincare Problem. The Journal of the Indian Mathematical Society, [S. l.], v. 22, n. 4, p. 181–205, 1958. DOI: 10.18311/jims/1958/16947. Disponível em: http://www.informaticsjournals.com/index.php/jims/article/view/16947. Acesso em: 30 apr. 2024.