Uzochukwu, John Sunday, et al. “Mathematical and Statistical Process Modeling of Hydrochloric Acid Leaching of Iron-Oxide Impurity from Inyi Kaolin: Response Surface Methodology”. International Journal of Modern Developments in Engineering and Science, vol. 2, no. 8, Aug. 2023, pp. 7-14, https://journal.ijmdes.com/ijmdes/article/view/168.