Singh, A.; Soni, K. D.; Singh, Y.; Aggarwal, R.; Venkateswaran, V. .; Ashar, M. S. .; Trikha, A. Alveolar Arterial Gradient and Respiratory Index in Predicting the Outcome of COVID-19 Patients; A Retrospective Cross-Sectional Study. Arch Acad Emerg Med 2022, 10, e28.