title: Letter: Upper gastrointestinal endoscopy.
mesh_terms: D001466:Barium Sulfate; D003258:Consumer Behavior; D004064:Digestive System; D004724:Endoscopy; D004945:Esophagoscopy; D005773:Gastroscopy; D006801:Humans; D011795:Surveys and Questionnaires
chemical_list: D001466:Barium Sulfate