STRÖMBECK, Peter. On the Spectral Category of Some Rings. MATHEMATICA SCANDINAVICA, [S. l.], v. 33, p. 213–228, 1973. DOI: 10.7146/math.scand.a-11485. Disponível em: https://tidsskrift.dk/math/article/view/11485. Acesso em: 13 aug. 2026.