Karunditu, Julia, George Kimathi, and Shaibu Osman. “Mathematical Modeling of Typhoid Fever Disease Incorporating Unprotected Humans in the Spread Dynamics”. Journal of Advances in Mathematics and Computer Science 32, no. 3 (May 16, 2019): 1-11. Accessed June 15, 2021. https://journaljamcs.com/index.php/JAMCS/article/view/30144.