GRONBAEK, Niels. Power factorization in Banach modules over commutative radical Banach algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 50, p. 123–134, 1982. DOI: 10.7146/math.scand.a-11949. Disponível em: https://journals.msp.org/mscand/article/view/1697. Acesso em: 25 jul. 2026.