Alfarisa, S., R.N. Safitri, and W.S.B. Dwandaru. 2016. “Effect of Catalyst Concentrations on the Growth of Carbon Nanotubes from Waste Engine Oil”. EDUCATUM Journal of Science, Mathematics and Technology 3 (1):6-12. https://ojs.upsi.edu.my/index.php/EJSMT/article/view/39.