Naoum, R.S., and L.N.M. Ta wfiq. “Density and Approximation by Using Feed Forward Artificial Neural Networks”. Ibn AL-Haitham Journal For Pure and Applied Sciences, vol. 20, no. 1, Sept. 2017, pp. 146-59, https://jih.uobaghdad.edu.iq/index.php/j/article/view/1335.