Movaheedi, Zabihullah, and Behzad Heravi. “Numerical Analysis of Typhoid Fever Spread Using Runge-Kutta and Nonstandard Finite Difference Methods”. Afghanistan Journal of Infectious Diseases 3, no. 1 (January 21, 2025): 56–73. Accessed April 26, 2025. https://www.ajid.ghalib.edu.af/index.php/ajid/article/view/68.