Prabha, J., and A. Kumar. “Prevalence of Vitamin D Deficiency in Pregnancy and Its Relation With Adverse Pregnancy Outcome”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, vol. 9, no. 9, Aug. 2020, pp. 3718-23, doi:10.18203/2320-1770.ijrcog20203845.