Songthamwat, Srisuda. 2013. “Prevalence of Abnormal Prenatal Screening for Down Syndrome in Udonthani Hospital Using Nuchal Translucency and Biochemical Marker”. Srinagarind Medical Journal 23 (2):153-60. https://li01.tci-thaijo.org/index.php/SRIMEDJ/article/view/13066.