Cao , T., J.T. Weil, P. Maharjan, J. Lu, and C.N. Coon. “The Digestible Methionine and Cystine Requirements for Commercial Layers”. International Journal of Poultry Science 19, no. 5 (April 15, 2020): 232–243. Accessed September 22, 2025. https://ijpsjournal.org/index.php/ijps/article/view/2596.