Okolo, Patrick, and Onoja Abu. “ON OPTIMAL CONTROL AND COST-EFFECTIVENESS ANALYSIS FOR TYPHOID FEVER MODEL”. FUDMA Journal of Sciences 4, no. 3 (September 29, 2020): 437–445. Accessed October 22, 2026. https://fjs.fudutsinma.edu.ng/index.php/fjs/article/view/258.