Thepsuwan, Jongrak, and Apichart Chittacharoen. 2012. “Umbilical Cord Prolapse and Perinatal Outcomes”. Thai Journal of Obstetrics and Gynaecology 17 (3). Bangkok, Thailand:150-54. https://he02.tci-thaijo.org/index.php/tjog/article/view/1616.