FANG, Junsheng; HADWIN, Don; MA, Xiujuan. On spectra and Brown’s spectral measures of elements in free products of matrix algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 103, n. 1, p. 77–96, 2008. DOI: 10.7146/math.scand.a-15070. Disponível em: https://journals.msp.org/mscand/article/view/627. Acesso em: 24 jul. 2026.