RONNOW, Ulf. Remarks on Compact Mappings. Mathematica Scandinavica, Berkeley, CA, United States, v. 10, p. 217–220, 1962. DOI: 10.7146/math.scand.a-10529. Disponível em: https://journals.msp.org/mscand/article/view/2660. Acesso em: 25 jul. 2026.