Li Dongzhi, Liao Can, Ma Xiaoyan
Prenatal Diagnostic Center, Guangzhou Maternal and Neonatal Hospital, Guangzhou Medical College, Guangzhou, Guangdong, China.
Int J Gynaecol Obstet. 2005 Dec;91(3):268-70. doi: 10.1016/j.ijgo.2005.08.011. Epub 2005 Oct 7.