V S V, Naga soundarya lakshmi, and Sabarmathi A. “Analysis of Seir Model With a Single Control for COVID-19”. Journal of Computational Mathematica 5, no. 1 (June 18, 2021): 28 - 37. Accessed September 26, 2021. https://www.shcpub.in/index.php/cm/article/view/116.