Tongsong, T., Wanapirak , C., Sirichotiyakul , S., & Chanprapaph, P. (1997). Prenatal Sonographic Features of Trisomy 18. Thai Journal of Obstetrics and Gynaecology, 9(4), 277–283. retrieved from https://he02.tci-thaijo.org/index.php/tjog/article/view/257208