Marwan, Marwan, Naoto Azuma, Akinori Maezawa, and Shigeo Uchida. 2003. “Characterization of Titania (TiO2) Catalysts Prepared by Sol-Gel Method”. ASEAN Journal of Chemical Engineering 3 (1), 26-33. https://jurnal.ugm.ac.id/v3/AJChE/article/view/7576.