Tongsong, T., Wanapirak , C., Sirichotiyakul , S. and Chanprapaph, P. (1997) “Prenatal Sonographic Features of Trisomy 18”, Thai Journal of Obstetrics and Gynaecology. Bangkok, Thailand, 9(4), pp. 277–283. available at: https://he02.tci-thaijo.org/index.php/tjog/article/view/257208 (accessed: 28 September 2026).