3Rotmensch S.,Liberati M.,Bronshtein M.el al.Prenatal sonographicfindings in 187 fetuses with Down syndrome.Prenatal Diagn,1997,17(11):1001~1009
4Cole L.A.,Acuna E.,Isozaki T.et al.Combining β-core fragment andtotal oestriol measurement to test for Down syndrome pregnancies.Prenatal Diagn,1997,17(12):1125~1133