Ahmed, Ghuzlan Sarhan, et al. “Study the Optical Properties of Polymer Poly Vinyl Alcohol Doped With CuO and Fe2Cl3 Thin Films”. Ibn AL-Haitham Journal For Pure and Applied Sciences, vol. 29, no. 3, Dec. 2016, pp. 345-54, https://jih.uobaghdad.edu.iq/index.php/j/article/view/728.