FORNAESS, John Erik. Uniform Approximation on Manifolds. Mathematica Scandinavica, Berkeley, CA, United States, v. 31, p. 166–170, 1972. DOI: 10.7146/math.scand.a-11422. Disponível em: https://journals.msp.org/mscand/article/view/2220. Acesso em: 25 jul. 2026.