Helicobacter (Campylobacter) pylori Infestation and the Development and Progression of Chronic Gastritis: Results of Long-term Follow-up Examinations of a Random Sample - Villako, K; Maards, H; Tammur, R; Keevallik, R; Peetsalu, M; Sipponen, P; Kekki, M; Siurala, M (Endoscopy, 1990)