1. Uber die peptischen;Falconer, B.,1943
2. The Acute and Chronic Peptic Lesions of the Stomach and the Duodenum. Uitgeverij Excelsior, The Hague;Levij, I.S.,1959
3. Levij, I. S. and Straub, M. (1957). Docum. Med. geogr. trop., (Amst.), 9, 369.
4. Watkinson, G. (1958). Schweiz. Z. Path., 21, 405.