Simanjuntak, L., B. C. Simanjuntak, and S. N. Lumbanraja. “Comparison of Serum Vitamin D Level Between Normal Pregnancy and Abortion in Outpatient Settings”. Open Access Macedonian Journal of Medical Sciences, vol. 10, no. B, May 2022, pp. 1538-42, doi:10.3889/oamjms.2022.9821.