[Ultrasonography during the 1st trimester of pregnancy: optimal contribution between the 12th and 13th week of gestation].
Gelin
V
V
Centre d'échographie, Boulogne.
Bussière
P
P
D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D016216:Ultrasonography, Prenatal