Priya Baghel, V. H. Badshah, T. K. Jhala, and Shivram Sharma. “A Mathematical Model of Typhoid With Drug Resistance Effect”. International Journal of Mathematics And Its Applications, vol. 5, no. 4 - E, Dec. 2017, pp. 793-9, https://ijmaa.in/index.php/ijmaa/article/view/1339.