Ngakan Putu Parsama Putra, Aditya Sri Listyoko, and Anthony Christanto. “PaO2, SaO2, and PaO2/FiO2 Ratio As A Predictor Disease Severity in Hospitalized COVID-19 Patients”. Journal Of The Indonesian Medical Association, Vol. 70, no. 12, Jan. 2021, pp. 253-9, doi:10.47830/jinma-vol.70.12-2020-326.