1. ACOG Committee Opinion: Maternal serum alpha-fetoprotein. Number 76, November 1989
2. No specific maternal serum pattern associated with trisomy 13 pregnancies;Blitzer;Am J Hum Genet,1992
3. Abnormal maternal serum human chorionic gonadotropin levels in pregnancies with fetal chromosome abnormalities;Bogart;Prenat Diagn,1987
4. Multiple-marker screening for fetal Down syndrome;Canick;Contemporary Obstetrics and Gynecology,1992
5. Low second-trimester levels of maternal serum estriol in Down syndrome pregnancies;Canick;Am J Hum Genet,1987