1. Hammeter, J. C.:Johns Hopkins Hosp. Bull., 7:79, April, 1896.
2. Kuhn, F.: Sondierungen am Magen, Pylorus and Duodenum des Menschen.Archiv. f. Verdauungskr., p. 19, 1898. (Quoted by Max Einhorn in. “The Duodenal Tube,” W. B. Saunders Co., Philadelphia, 1920).
3. Gross, Maurice: A Duodenal Tube.New York Med. J., 91:77, Jan. 8, 1910.
4. Einhorn, Max: A Practical Method of Obtaining Duodenal Contents in Man.Medical Record, 77:98, Jan. 15, 1910.
5. Einhorn, Max: A New Method of Estimating the Permeability of the Pylorus and an Attempt at Testing the Pancreatic Function Directly.New York Med. J., 87:1179, June 20, 1908.