Kamwilaisak, K., and P. Thiamsinsangwon. “Preparation of nanostructured crystalline titanium dioxide (TiO2) by Sol-Gel technique”. Engineering and Applied Science Research, vol. 40, no. 2, June 2014, pp. 147-53, https://ph01.tci-thaijo.org/index.php/easr/article/view/19091.