HANF, W. On some fundamental problems concerning isomorphism of Boolean algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 5, p. 205–217, 1957. DOI: 10.7146/math.scand.a-10496. Disponível em: https://www.mscand.dk/article/view/10496. Acesso em: 4 may. 2024.