SEN, R. N. On a Type of Riemannian Space Conformal to a Flat Space. The Journal of the Indian Mathematical Society, [S. l.], v. 21, n. 3-4, p. 105–114, 1957. DOI: 10.18311/jims/1957/16963. Disponível em: http://informaticsjournals.com/index.php/jims/article/view/16963. Acesso em: 28 apr. 2024.