KEHLET, E. T. On the Monotone Sequential Closure of a $C^*$-Algebra. MATHEMATICA SCANDINAVICA, [S. l.], v. 25, p. 59–70, 1969. DOI: 10.7146/math.scand.a-10941. Disponível em: https://www.mscand.dk/article/view/10941. Acesso em: 2 may. 2024.