title: Letter: Upper-gastrointestinal endoscopy.
mesh_terms: D001466:Barium Sulfate; D004724:Endoscopy; D005069:Evaluation Studies as Topic; D005767:Gastrointestinal Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging; D006801:Humans; D011859:Radiography
chemical_list: D001466:Barium Sulfate