Decline of serum human chorionic gonadotropin and spontaneous complete abortion: defining the normal curve.
Barnhart K, Sammel MD, Chung K, Zhou L, Hummel AC, Guo W. Decline of serum human chorionic gonadotropin and spontaneous complete abortion: defining the normal curve. Obstet Gynecol. 2004 Nov; 104(5 Pt 1):975-81.