Vaccaro, Rosa, Carola Severi, Giuditta Serrao, Marilia Carabotti, Arianna Casini, Piero Chirletti, and Paolo Onori. 2016. “Endocrine Cells Distribution in Human Proximal Small Intestine: An Immunohistochemical and Morphometrical Study”. Italian Journal of Anatomy and Embryology 121 (1):112-21. https://oajournals.fupress.net/index.php/ijae/article/view/1575.