ARA, Pere; PERERA, Francesc. Non-stable $K$-theory for $QB$-rings. Mathematica Scandinavica, Berkeley, CA, United States, v. 100, n. 2, p. 265–300, 2007. DOI: 10.7146/math.scand.a-15024. Disponível em: https://journals.msp.org/mscand/article/view/673. Acesso em: 24 jul. 2026.