Kikawa, C. R., and P. H. Kloppers. “Multiple Linear Regression With Constrained Coefficients: Application of the Lagrange Multiplier”. South African Statistical Journal 50, no. 2 (September 30, 2016): 303–312. Accessed April 3, 2026. https://www.journals.ac.za/index.php/sasj/article/view/5259.