Alhassan, A., Momoh, A. A., Abdullahi, S. A., and Audu, A. “Mathematical Model for the Transmission Dynamics of Typhoid Fever Infection With Treatment”. International Journal of Science for Global Sustainability, vol. 7, no. 2, July 2021, p. 13, https://www.fugus-ijsgs.com.ng/index.php/ijsgs/article/view/25.