W. Issa , Yasir, and Shahlaa M. Salih. “Evaluating the Effectiveness of Pfizer, AstraZeneca, and Sinopharm Vaccines Against COVID-19 in Iraq: A Cross-Sectional Study of Vaccine Efficacy and Symptom Severity”. Journal of Madenat Alelem University College 16, no. 1 (May 1, 2024): 11-21. Accessed December 22, 2024. http://116.203.176.164/index.php/JMAUC/article/view/507.