Precise gaussian distribution functions of maternal serum alpha-fetoprotein and free beta-subunit of human chorionic gonadotropin for trisomy 21 screening: improved accuracy for patient counseling.
Chik L, Spencer K, Johnson MP, Ayoub M, Krivchenia EL, Dombrowski MP, Sokol RJ, Evans MI. Precise gaussian distribution functions of maternal serum alpha-fetoprotein and free beta-subunit of human chorionic gonadotropin for trisomy 21 screening: improved accuracy for patient counseling. Am J Obstet Gynecol. 1997 Oct; 177(4):882-6.