Dhobale, Snehal S., and Meena Satia. 2017. “Effectiveness of Cervical Length Screening by Transvaginal Sonography and Use of Progesterone for Preventing Preterm Labour”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology 5 (8):2813-18. https://doi.org/10.18203/2320-1770.ijrcog20162672.