Atjimakul, Thiti, and Tippawan Liabsuetrakul. 2012. “Risk Factors for Two Consecutive Preterm Births in Southern Thailand”. Thai Journal of Obstetrics and Gynaecology 18 (3). Bangkok, Thailand:98-105. https://he02.tci-thaijo.org/index.php/tjog/article/view/1352.