8Benacerraf BR. The second trimester fetus with down syndrome:detection using sonographic features. Ultrasound Obstet Gynecol, 1996,7 : 147-155.
9Baronciani D, Scaglia C, Corchia C, et al . Ultrasonography in pregnancy and fetal abnormalities: screening or diagnostic test? IPIMC 198621990 register data. Indagine Policentriea Italiana sulle Malformazioni Congenite. Prenat Diagn, 1995, 15 (12): 1101-1108.
10Ploeckinger-Ulm B, Ulm MR, Lee A, Kratochwil A, Bernaschek G. Antenatal depiction of fetal digit with threedimensional ultrasonography. Am J Obstet Gynecol, 1996,175:571-574.