Tjandra, H., and E. Sarwono. “Single Step Gastric Aspirate Shake Test As a Screening Procedure for Predicting the Risk of Neonatal Respiratory Distress”. Paediatrica Indonesiana, Vol. 21, no. 3-4, Apr. 1981, pp. 69-80, doi:10.14238/pi21.3-4.1981.69-80.