Iype, Mercy, Shaji Varghese, E.J. Mathew, and C.S. Menon. 2010. “Temperature Dependence of the Activation Energy of Thin Films of Zinc Sulphide, Copper Phthalocyanine and Multi- Layer Zinc Sulphide-Copper Phthalocyanine ”. Asian Journal of Chemistry 14 (3):1667-72. https://asianpubs.org/index.php/ajchem/article/view/22458.