ON OPTIMAL CONTROL AND COST-EFFECTIVENESS ANALYSIS FOR TYPHOID FEVER MODEL. FUDMA JOURNAL OF SCIENCES, [S. l.], v. 4, n. 3, p. 437–445, 2020. DOI: 10.33003/fjs-2020-0403-258. Disponível em: http://www.fjsadmin.fudutsinma.edu.ng/index.php/fjs/article/view/258. Acesso em: 11 sep. 2025.