B. P. Thangappah, Radha, Ursula Sampson, Amrin Azad, Rathna Arumugam, Smriti Anand, and Ponnalagan Karunakaran. “A Study to Evaluate Serum 25-Hydroxy Vitamin D3 and Calcium Levels in Maternal and Cord Blood and Their Effect on Pregnancy Outcome”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology 8, no. 4 (March 26, 2019): 1575–1582. Accessed October 13, 2025. https://www.ijrcog.org/index.php/ijrcog/article/view/6201.