Mishra, A. A., and S. N. Chaudhari. “Vaginal Progesterone After Tocolytic Therapy in Threatened Preterm Labour”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, vol. 9, no. 8, July 2020, pp. 3233-8, doi:10.18203/2320-1770.ijrcog20203301.