H. F. . Al-husseiny, “Global Stability of an epidemic model with vaccine involving stage structure”, Iraqi Journal of Science, vol. 57, no. 4C, pp. 2922–2931, Jan. 2022, Accessed: Dec. 07, 2025. [Online]. Available: https://www.ijs.uobaghdad.edu.iq/index.php/eijs/article/view/6279