Zaman, Uzma, et al. “ASSOCIATION OF RISK FACTORS WITH SPONTANEOUS PRETERM LABOUR WITH INTACT FOETAL MEMBRANES”. Journal of Ayub Medical College Abbottabad, vol. 31, no. 4, Sept. 2019, pp. 536-40, https://www.jamc.ayubmed.edu.pk/index.php/jamc/article/view/5944.