Zhaoshen Li et al. Epidemiology of Peptic Ulcer Disease: Endoscopic Results of the Systematic Investigation of Gastrointestinal Disease in China. Am J Gastroenterol, doi:10.1038/ajg.2010.324
[2](1,2) Susan Levenstein. The Very Model of a Modern Etiology: A Biopsychosocial View of Peptic Ulcer. Psychosomatic Medicine 62:176-185 (2000)