Echoes from the past: history of obstetric ultrasound.
Nelson
Lewis H
LH
American Institute of Ultrasound in Medicine, USA.
D005260:Female; D049673:History, 20th Century; D006801:Humans; D009774:Obstetrics / Q000266:history*; D011247:Pregnancy; D016216:Ultrasonography, Prenatal / Q000266:history*