Sferra, Roberta, et al. “Role of TGFβ1 Smads Pathway in the Pathogenesis of Intestinal Fibrosis in Crohn’s Disease”. Italian Journal of Anatomy and Embryology, vol. 117, no. 2, Feb. 2013, p. 178, https://oajournals.fupress.net/index.php/ijae/article/view/4364.