Fatimah, Is. “Preparation of ZnO Cetyl Trimethyl Ammonium Salt Hectorite As Catalyst in Alizarin Red S Photo-Oxidation”. Asian Journal of Chemistry, vol. 23, no. 10, Aug. 2011, pp. 4672-6, https://asianpubs.org/index.php/ajchem/article/view/10945.