AHMED MAHMOUD, M. M. ,. Dept. of Mathematics, S. V. University, Tirupati, Andhra Pradesh, India. International Journal of Engineering and Computer Science, india, v. 2, n. 7, 2013. Disponível em: http://ijecs.in/index.php/ijecs/article/view/1667. Acesso em: 19 may. 2024.