Thorpe-Beeston J G, Nicolaides K H, Gosden C M, McGregor A M
Harris Birthright Research Centre for Fetal Medicine, Department of Obstetrics and Gynaecology, King's College School of Medicine and Dentistry, London.
BMJ. 1991 Mar 16;302(6777):628. doi: 10.1136/bmj.302.6777.628.