STØRMER, Erling. Multiplicative properties of positive maps. Mathematica Scandinavica, Berkeley, CA, United States, v. 100, n. 1, p. 184–192, 2007. DOI: 10.7146/math.scand.a-15020. Disponível em: https://journals.msp.org/mscand/article/view/677. Acesso em: 26 aug. 2026.