DYKEMA, Kenneth J. Purely Infinite, Simple $C^*$-Algebras Arising from Free Product Constructions, II. Mathematica Scandinavica, Berkeley, CA, United States, v. 90, n. 1, p. 73–86, 2002. DOI: 10.7146/math.scand.a-14362. Disponível em: https://journals.msp.org/mscand/article/view/857. Acesso em: 24 jul. 2026.