1. Karzinoid tumoren des Dunndarms;Oberndorfer;Frankfurter Zietshrift fur Pathologie,1907
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3. The APUD cell concept and its implications in pathology;Pearse;Path Ann,1974
4. Neuroendocrinomas: APUD-cell system neoplasms and their aberrant secretory activities;Gould;Path Annul,1977
5. Diagnostic Transmission Electron Microscopy of Tumors;Erlandson,1994