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First-trimester screening for trisomy 21 using nuchal translucency and nasal bone evaluations in a selected and an unselected population.
Sonek J, Cicero S, Nicolaides K.
Am J Obstet Gynecol 2007;196:19. -
Down's syndrome screening with nuchal translucency.
Nicolaides KH, Sebire NJ, Snijders RJ.
Lancet 1997;349:438.