Rattan, G., and R. Prasad. “Study the Effect on Activity of Alumina Supported CuO-CeO2-ZrO2 Catalysts Prepared by Four Methods for CO Oxidation”. ASEAN Journal of Chemical Engineering, Vol. 13, no. 2, Dec. 2013, pp. 39-49, https://dev.journal.ugm.ac.id/v3/AJChE/article/view/8155.