ASSAF, AHMED M.; SHALABY N.; YIN J. On directed packing designs with block size 5 and index λ = 2. Utilitas Mathematica , [S. l.], v. 50, 1996. Disponível em: https://utilitasmathematica.com/index.php/Index/article/view/31. Acesso em: 8 may. 2026.