9Rychik J, Ayres N, Cuneo B,et al. American society of echo- cardiography guidelines and standards for performance of the fetal echocardiogram [ J ]. Am Soc Echocardiogram, 2004,17 (7) :803-810.
10Gottliebson WM, Border WI , Franklin CM ,et al. Accuracy of fetal echocardiography : a cardiac segment- specific analysis [ J]. Ultrasound Obestrt Gyneco1,2006,28 : 15-21.