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 May 6, 2024. https://fjs.fudutsinma.edu.ng/index.php/fjs/article/view/258.