., K., D. Kumar, A. Verma, S. Chaurasia, and R. Nag. “Cervical Sonomorphometric Evaluation of Normal and Preterm Labour by Transvaginal and Transabdominal Sonography”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, vol. 6, no. 2, Jan. 2017, pp. 417-22, doi:10.18203/2320-1770.ijrcog20170042.