Thitadilok, Wiboolphan, Kitirat Techatraisak, and Ronnachai Atisook. 1993. “Clinical Evaluation of Prostaglandin E, Gel for Preinduction Cervical Ripening in Term Pregnancy with a Low Bishop Score”. Thai Journal of Obstetrics and Gynaecology 5 (2). Bangkok, Thailand:67-71. https://he02.tci-thaijo.org/index.php/tjog/article/view/257808.