Gorgess, H. M., and A. I. Abdul Naby. “Using Restricted Least Squares Method to Estimate and Analyze the Cobb-Douglas Production Function With Application”. Ibn AL-Haitham Journal For Pure and Applied Sciences, vol. 25, no. 2, May 2017, https://jih.uobaghdad.edu.iq/index.php/j/article/view/644.