HANF, William. 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://tidsskrift.dk/math/article/view/10496. Acesso em: 14 aug. 2026.