LINDSTRÖM, B. On Group and Nongroup Perfect Codes in $q$ Symbols. MATHEMATICA SCANDINAVICA, [S. l.], v. 25, p. 149–158, 1969. DOI: 10.7146/math.scand.a-10952. Disponível em: https://www.mscand.dk/article/view/10952. Acesso em: 29 apr. 2024.