BUCKLEY, Stephen M.; HANSON, Bruce; MACMANUS, Paul. Doubling for general sets. MATHEMATICA SCANDINAVICA, [S. l.], v. 88, n. 2, p. 229–245, 2001. DOI: 10.7146/math.scand.a-14324. Disponível em: https://www.mscand.dk/article/view/14324. Acesso em: 5 dec. 2025.