Mainguet, P., Debongnie, JC., Jouret, A., & Haot, J. (1987). [Endoscopy for Crohns-disease of the Upper Digestive-tract]. Acta Gastro-Enterologica Belgica (Multilingual Edition), 50(5), 491-497. https://hdl.handle.net/2078.5/139649 (Original work published 1987)