S. M. Rangkuti, N. Nazir, A. H. Sutanto, A. Lubis, and H. Siregar, “Measles Morbidity and Mortality in the Department of Child Health, Dr. Pirngadi General Hospital, Medan, in 1973-1977”, PI, vol. 20, no. 7-8, pp. 139-44, Dec. 2021.