HEDEN, O. A generalized Lloyd theorem and mixed perfect codes. MATHEMATICA SCANDINAVICA, [S. l.], v. 37, p. 13–26, 1975. DOI: 10.7146/math.scand.a-11583. Disponível em: https://www.mscand.dk/article/view/11583. Acesso em: 2 may. 2024.