Klebermass-Schrehof K, Wald M, Schwindt J, Grill A, Prusa AR, Haiden N, Hayde M, Waldhoer T, Fuiko R, Berger A. Less invasive surfactant administration in extremely preterm infants: impact on mortality and morbidity. Neonatology. 2013;103(4): 252-258. PubMed: 23446061