PFEFFER, W. F. An Integral in Topological Spaces II. Mathematica Scandinavica, Berkeley, CA, United States, v. 27, p. 77–104, 1970. DOI: 10.7146/math.scand.a-10989. Disponível em: https://journals.msp.org/mscand/article/view/2338. Acesso em: 25 jul. 2026.