Centurione, Maria Antonietta, et al. “Embryoid Body in Vitro Formation from Human Amniotic Fluid Stem Cells (AFSCs): An Ultrastructural Study”. Italian Journal of Anatomy and Embryology, vol. 118, no. 2, Jan. 2014, p. 53, https://oajournals.fupress.net/index.php/ijae/article/view/3515.