7Stafford IA,Dashe JS,Shivvers SA.Ultrasonographic cervical length and risk of hemorrhage in pregnancies with placenta previa[J].Obstet Gynecol,2010 Sep:116(3):595-600.
8Law LW,Chor CM,Leung TY.Use of hemostatic gel in postpartum hemorrhage due to placenta previa[J].Obstet Gynecol,2010,116(2):528-530.
9Comstock CH.Antenatal diagnosis of placenta accreta:a review[J].Ultrasound Obstet Gynecol,2005,26(1):89-96.