PUTNAM, I. F.; RORDAM, M. The maximum unitary rank of some $C^*$-algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 63, p. 297–304, 1988. DOI: 10.7146/math.scand.a-12242. Disponível em: https://www.mscand.dk/article/view/12242. Acesso em: 29 apr. 2024.