“Effect of Transition Metal Oxide Doping (Cr, Co, V) in the Photocatalytic Activity of TiO2 for Congo Red Degradation under Visible Light”. Jurnal Teknologi 69, no. 5 (July 2, 2014). Accessed July 23, 2024. https://journals.utm.my/jurnalteknologi/article/view/3203.