T. Nachaithong, P. Sikam, P. Moontragoon, P. Thongbai, T. Kaewmaraya, and Z. Ikonic, “The study of optical and colossal dielectric properties of (Cu, Ga)-doped ZnO nanoparticles”, Eng Appl Sci Res, vol. 48, no. 6, pp. 759–765, Jul. 2021.