Wong H S, Zuccollo J, Parker S, Burns K, Tait J, Pringle K C
Department of Obstetrics and Gynaecology, Wellington School of Medicine and Health Sciences, University of Otago, New Zealand.
Ultrasound Obstet Gynecol. 2006 Apr;27(4):467-9. doi: 10.1002/uog.2759.