O. Eguasa, J. I. Mbegbu, and E. Edionwe, “On the use of nonparametric regression model in Response Surface Methodology”, BJS, vol. 2, no. 1, pp. 61– 75, Jan. 2019, Accessed: Dec. 16, 2025. [Online]. Available: https://www.bjs-uniben.org/index.php/home/article/view/13