Interobserver agreement on classifying endoscopic diagnoses of nonerosive esophagitis - Amano, Y; Ishimura, N; Furuta, K; Okita, K; Masaharu, M; Azumi, T; Ose, T; Koshino, K; Ishihara, S; Adachi, K; Kinoshita, Y (Endoscopy, 2006)