M. A. Khoiri, S. N. Lumbanraja, D. Aldiansyah, M. F. G. Siregar, M. Sitepu, and M. R. Tala, “Calcium serum concentration among pregnant women in a tertiary hospital and its satellite hospital in Medan, Indonesia”, MOG, vol. 30, no. 2, pp. 78–83, Aug. 2022.