Guzman E R, Day-Salvatore D, Westover T, Rosenberg J C, Beim D, Grabelle H
Division of Maternal-Fetal Medicine, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey 08903-0591, USA.
J Ultrasound Med. 1994 Jan;13(1):63-6. doi: 10.7863/jum.1994.13.1.63.