Sutjipto, A., Purba, D., Nazir, N., Purba, M.D. and Siregar, H. 1981. A survey on breastfeeding practices at Dr. Pirngadi Hospital Medan. Paediatrica Indonesiana. 21, 3-4 (Apr. 1981), 51-60. DOI:https://doi.org/10.14238/pi21.3-4.1981.51-60.