GRAU, José María. Variations on Giuga Numbers and Giuga’s Congruence. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 67, n. 11, p. 1573–1578, 2015. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2091. Acesso em: 5 dec. 2025.