HEDEN, Olof. Perfect Codes in Antipodal Distance-Transitive Graphs. MATHEMATICA SCANDINAVICA, [S. l.], v. 35, p. 29–37, 1974. DOI: 10.7146/math.scand.a-11532. Disponível em: https://tidsskrift.dk/math/article/view/11532. Acesso em: 13 aug. 2026.