GRANNELL M.J.; GRIGGS T.S.; STANTON R.G.; WHITEHEAD C.A. On the covering number g 1 (4)(18). Utilitas Mathematica , [S. l.], v. 68, 2005. Disponível em: https://utilitasmathematica.com/index.php/Index/article/view/353. Acesso em: 8 may. 2026.