4An-Shine Chao,Chao-Lung Chung,Chien-Der Wu,ShuennDyh Chang,Po-Jen Cheng,Yu-Ting Lin,Yung-Kuei Soong.Second trimester maternal serum screening using alpha fetoprotein, free beta human chorionic gonadotropin and maternal age specific risk, Result of chromosomal abnormalities detected in screen positive for Down syndrome in an Asian population. Acta obstetricia et gynecologica Scandinavica . 1999
5DaveWright,IanBradbury,PeterBenn,HowardCuckle,KarenRitchie.??Contingent screening for Down syndrome is an efficient alternative to non‐disclosure sequential screening(J)Prenat. Diagn. . 2004 (10)