Raad Saadi, Rami, and Hassan F. Al-Husseiny. “Influence of Infection Delay on the Covid-19 Pandemic With Vaccination Control: Modeling and Simulation”. Ibn AL-Haitham Journal For Pure and Applied Sciences 38, no. 1 (April 20, 2025): 445–464. Accessed May 1, 2025. https://www.jih.uobaghdad.edu.iq/index.php/j/article/view/3638.