VAN DER PUTTEN, Roberto. A note on the local invertibility of Sobolev functions. Mathematica Scandinavica, Berkeley, CA, United States, v. 83, n. 2, p. 255–264, 1998. DOI: 10.7146/math.scand.a-13854. Disponível em: https://journals.msp.org/mscand/article/view/974. Acesso em: 25 jul. 2026.