1. The Principles and Practice of Ultrasonography in Obstetrics and Gynecology. 3rd ed.;Sanders,1985
2. Ultrasound in Obstetrics and Gynecology;Chitty,1993
3. Prenatal Diagnosis of Congenital Anomalies;Romero,1988
4. Detection of cleft lip by early second-trimester transvaginal sonography;Bronshtein;Obstet Gynecol,1994
5. Effectiveness of routine ultrasonography in detecting fetal structural abnormalities in a low risk population;Chitty;BMJ,1991