1. Antepartum fetal surveillance;American College of Obstetricians and Gynecologists,1994
2. Improved outcome of twice weekly nonstress testing;Boehm;Obstet Gynecol,1986
3. Amniotic fluid volume assessment with the four-quadrant technique at 36-42 weeks’ gestation;Phelan;J Reprod Med,1987
4. Nonstress testing with acoustic stimulation and amniotic fluid volume assessment: 5973 tests without unexpected fetal death;Clark;Am J Obstet Gynecol,1989
5. The four-quadrant assessment of amniotic fluid volume: an adjunct to antepartum fetal heart rate testing;Rutherford;Obstet Gynecol,1987