Mathew, S. M., and A. Kumar. “A Prospective Analysis of the Risk Factors and the Perinatal Outcome of Preterm Labour”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, vol. 7, no. 12, Nov. 2018, pp. 4833-9, doi:10.18203/2320-1770.ijrcog20184924.