et.al, H. T. K. “Study of the Effect of Thickness and Annealing Process on Optical Properties of (SnO2:5%Cu) Thin Films”. Al-Qadisiyah Journal of Pure Science, Vol. 18, no. 2, Aug. 2017, pp. 113-27, https://journalsc.qu.edu.iq/index.php/JOPS/article/view/426.