Karim, Lt Col Farhat, et al. “EFFICACY OF CERVICAL CERCLAGE USING MCDONALD’S TECHNIQUE IN PREVENTING PRETERM BIRTHS: Cervical Cerclage”. Pakistan Armed Forces Medical Journal, vol. 62, no. 2, June 2012, pp. 267-70, https://www.pafmj.org/PAFMJ/article/view/1727.