Halim, L., S. Sayogo, and H. Handaja. “Relationship Between Calcium Intake, Serum Ionized Calcium and Elevated Blood Pressure in Primigravida After 24 Weeks of Gestation”. Medical Journal of Indonesia, vol. 6, no. 4, Oct. 1997, pp. 216-20, doi:10.13181/mji.v6i4.830.