CECCHINI, Carlo. An abstract characterization of $\omega$-conditional expectations. Mathematica Scandinavica, Berkeley, CA, United States, v. 66, p. 155–160, 1990. DOI: 10.7146/math.scand.a-12300. Disponível em: https://journals.msp.org/mscand/article/view/1320. Acesso em: 24 jul. 2026.