Abdullah, A. Z., M. Z. Abu Bakar, and S. Bhatia. “Perfomance of Chromium-Exchanged Zeolite Catalysts in the Combustion of Volatile Organic Compound Pollutants”. ASEAN Journal of Chemical Engineering, Vol. 4, no. 2, Dec. 2004, pp. 66-74, https://journal.ugm.ac.id/v3/AJChE/article/view/7626.