Koranantakul , Ounjai, Rawiwan Rattanapreuksachart, and Prasin Chanvita. 1991. “Fetal Biparietal Diameters in Normal Pregnant Southern Thai Women”. Thai Journal of Obstetrics and Gynaecology 3 (2). Bangkok, Thailand:71-77. https://he02.tci-thaijo.org/index.php/tjog/article/view/257860.