AL-SAIDY, S. K.; HAMOOD, A. A. Approximation Properties of the Strong Difference Operators. Ibn AL-Haitham Journal For Pure and Applied Sciences, Baghdad, Iraq., v. 25, n. 1, 2017. Disponível em: https://jih.uobaghdad.edu.iq/index.php/j/article/view/689.. Acesso em: 27 sep. 2024.