Ovarian follicular concentrations of activin, follistatin, inhibin, insulin-like growth factor I (IGF-I), IGF-II, IGF-binding protein-2 (IGFBP-2), IGFBP-3, and vascular endothelial growth factor in spontaneous menstrual cycles of normal women of advanced reproductive age - Klein,N.A.; Battaglia,D.E.; Woodruff,T.K. (J Clin Endocrinol Metab, 2000)