STROM, Arne. Note on Cofibrations II. Mathematica Scandinavica, Berkeley, CA, United States, v. 22, p. 130–142, 1968. DOI: 10.7146/math.scand.a-10877. Disponível em: https://journals.msp.org/mscand/article/view/2424. Acesso em: 25 jul. 2026.