BROWN, Robert F. On Suitable Manifolds. Mathematica Scandinavica, Berkeley, CA, United States, v. 14, p. 174–178, 1964. DOI: 10.7146/math.scand.a-10715. Disponível em: https://journals.msp.org/mscand/article/view/2593. Acesso em: 25 jul. 2026.