VAROPOULOS, N. Th. A theorem on operator algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 37, p. 173–182, 1975. DOI: 10.7146/math.scand.a-11599. Disponível em: https://journals.msp.org/mscand/article/view/2073. Acesso em: 25 jul. 2026.