Siregar, H., A. Lubis, M. A. Nasution, I. K. Nasution, and T. Tanjung. “Family Size and Marital Age”. Paediatrica Indonesiana, vol. 25, no. 5-6, Apr. 2019, pp. 107-11, doi:10.14238/pi25.5-6.1985.107-11.