Vannucchi, M., L. Cinci, and M. Faussone-Pellegrini. “Inhibitory and Excitatory Enteric Neurons of the Mouse Duodenum Co-Express the Glucagon-Like Peptide 1 or Glucagon-Like Peptide 2 Receptors”. Italian Journal of Anatomy and Embryology, vol. 115, no. 1/2, Nov. 2010, p. 174, https://oajournals.fupress.net/index.php/ijae/article/view/4559.