Dr. N. Sriram, Dr. S. Kameshwaran, and Ebenezer David. “Worldwide Covid-19 Approved Vaccines - A Comprehensive Review on Corona Virus Vaccines”. International Journal of Allied Medical Sciences and Clinical Research 9, no. 2 (May 9, 2021): 207–212. Accessed April 18, 2024. https://ijamscr.com/ijamscr/article/view/993.