Abstract

References
1.
McGahan J
,
Porto M
:Diagnostic Obstetrical Ultrasound . Philadelphia : Lippincott-Raven , 1994 , pp 246 –248 .
2.
Berman M
,
Cohen H
:Obstetrics and Gynecology . Philadelphia : Lippincott-Raven , 1997 , pp 289 –290 .
3.
Sanders
:Structural Fetal Abnormalities . St. Louis, MO : 1996 , pp 118 –120 .
