Shah, P.; Ganguly, R.; Jain, L. K.; Patel, K.; Patel, K.; Chauhan, D. An Observational Study on Perfusion Index to Predict and Correlate Incidences of Hypotension Following Spinal Anaesthesia Using Pulse Oximeter. Int. J. of Health Sci. 2022, 6, 3075-3082.