1Fergal D Malone,Mary E D’Alton.First-Trimester Sonographic Screening for Down Syndrome[J].Obstetrics & Gynecology.2003(5)
2Parano E,Falcidia E,Grillo A,Pavone P,Cutuli N,Takabayashi H,Trifiletti R R,Gilliam C T.Noninvasive prenatal diagnosis of chromosomal aneuploidies by isolation and analysis of fetal cells from maternal blood[].American journal of medical genetics.2001