Narrow-band imaging with magnification in Barrett’s esophagus: validation of a simplified grading system of mucosal morphology patterns against histology - Singh, R; Anagnostopoulos, G K; Yao, K; Karageorgiou, H; Fortun, P J; Shonde, A; Garsed, K; Kaye, P V; Hawkey, C J; Ragunath, K (Endoscopy, 2008)