On the gracefulness of the digraphs n − C m for m odd. Journal of Prime Research in Mathematics, [S. l.], v. 4, n. 1, p. 118 – 126, 2008. Disponível em: https://jprm.sms.edu.pk/index.php/jprm/article/view/39. Acesso em: 4 feb. 2026.