Waluyo, J., T. Richards, I. Makertihartha, and H. Susanto. “Modification of Natural Zeolite As a Catalystfor Steam Reforming of Toluene”. ASEAN Journal of Chemical Engineering, Vol. 17, no. 1, June 2017, pp. 37-45, https://journal.ugm.ac.id/v3/AJChE/article/view/8957.