Varghese, Vinod, Sonal Bhoyar, and Kottakkaran Sooppy Nisar. “Analysis of Fractional-Order Model of COVID-19 Pandemics With a Nonlinear Incidence Rate”. Innovative Biosystems and Bioengineering 4, no. 3 (September 23, 2020): 160–167. Accessed October 4, 2024. http://ibb.kpi.ua/article/view/206271.