HUSCH, L. S. Fibres of Hurewicz and approximate fibrations. Mathematica Scandinavica, Berkeley, CA, United States, v. 43, p. 44–48, 1978. DOI: 10.7146/math.scand.a-11761. Disponível em: https://journals.msp.org/mscand/article/view/1886. Acesso em: 25 jul. 2026.