“Structural, Optical and Raman Characterization of Nano-Crystalline Cu Doped ZnO Thin Films Deposited by Pulse Laser Deposition Technique”. Global Journal of Science Frontier Research, vol. 19, no. A9, Oct. 2019, pp. 43-49, https://www.journalofscience.org/index.php/GJSFR/article/view/2535.