A Score Card for Upper GI Endoscopy: Evaluation of Interobserver Variability in Examiners with Various Levels of Experience - Neumann, M; Friedl, S; Meining, A; Egger, K; Heldwein, W; Rey, J -F; Hochberger, J; Classen, M; Hohenberger, W; Rösch, T (Zeitschrift für Gastroenterologie, 2002)