Muench Michael V, Zheng Min, Bilica Paula M, Canterino Joseph C
Department of Obstetrics, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA.
J Ultrasound Med. 2008 Sep;27(9):1369-73. doi: 10.7863/jum.2008.27.9.1369.