Dhanasekara, C. S., S.-H. Chin, and C. N. Kahathuduwa. “Severity and Case Fatality Rates of COVID-19: A Systematic Review, Meta-Analysis and an Exploratory Meta-Regression of Risk Factors”. The Southwest Respiratory and Critical Care Chronicles, Vol. 9, no. 41, Oct. 2021, pp. 8-19, doi:10.12746/swrccc.v9i41.921.