Department of General and Abdominal SurgeryPhilip HedwigInstitute of Medical StatisticsAlexander J EckardtInstitute of Medical BiostatisticsKathrin KuhrJochem K nigVolker F Eckardt世界胃肠病学杂志:英文版Mu¨ller, M.; Gockel, I.; Hedwig, P.; et al. Is The Schatzki Ring a Unique Esophageal Entity?