STRÖMBECK, Peter. On the Spectral Category of Some Rings. Mathematica Scandinavica, Berkeley, CA, United States, v. 33, p. 213–228, 1973. DOI: 10.7146/math.scand.a-11485. Disponível em: https://journals.msp.org/mscand/article/view/2181. Acesso em: 25 jul. 2026.