1. Hüpscher DN:Radiology of the Esophagus. New York: Georges Thieme Verlag, 1988, pp 37–39
2. Ghahremani GG: Ingested foreign bodies: Radiological diagnosis and management. In: Thompson WM (ed):Common Problems in Gastrointestinal Radiology. Chicago: Year Book Medical Publishers, 1989, pp 152–162
3. Chaikhouni A, Kratz JM, Crawford FA: Foreign bodies of the esophagus.Am Surg 51:173–179, 1985