LAWRYNOWICZ, J.; WALISZEWSKI, W. Conformality and Pseudo-Riemannian Manifolds. MATHEMATICA SCANDINAVICA, [S. l.], v. 28, p. 45–69, 1971. DOI: 10.7146/math.scand.a-11005. Disponível em: https://www.mscand.dk/article/view/11005. Acesso em: 29 apr. 2024.