AHMAD, Abd Ghafur. Kumpulan Gambar Rajah Hasil Darab Langsung. MATEMATIKA, [S. l.], v. 18, p. 63–66, 2002. DOI: 10.11113/matematika.v18.n.496. Disponível em: https://matematika.utm.my/index.php/matematika/article/view/496. Acesso em: 8 apr. 2025.