Radulova, P., Slancheva, B. and Marinov, R. (2023) “Oxygenation Index – an Objective Indicator of the Severity and Treatment Effect of Persistent Pulmonary Hypertension of the Newborn”, Proceedings of the Bulgarian Academy of Sciences. Sofia, Bulgaria, 76(3), pp. 440–447. doi: 10.7546/CRABS.2023.03.13.