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 70, no. 12 (January 21, 2021): 253-259. Accessed May 15, 2021. http://mki-ojs.idionline.org/jurnal/article/view/326.