BUCKLEY, Stephen M.; HANSON, Bruce; MACMANUS, Paul. Doubling for general sets. Mathematica Scandinavica, Berkeley, CA, United States, v. 88, n. 2, p. 229–245, 2001. DOI: 10.7146/math.scand.a-14324. Disponível em: https://journals.msp.org/mscand/article/view/881. Acesso em: 24 jul. 2026.