1. Amniotic fluid volume assessment with the four-quadrant technique at 36-42 weeks' gestation;Phelan;J Reprod Med,1987
2. Parathyroid disorders of pregnancy;Mestman;Semin Perinatol,1998
3. Parathyroid hormone and parathyroid hormone-related peptide in venous umbilical cord blood of healthy neonates;Saxe;J Perinat Med,1997
4. Harrison's principles of internal medicine;Kaspe,2004
5. Calcium metabolism in pregnancy and the perinatal period: a review;Pitkin;Am J Obstet Gynecol,1985