1. Assmann, Herbert: Klinische Roentgendiagnostik der Inneren Krankheiten; 1924, 3rd Ed.; F. C. W. Vogel, Leipzig.
2. Barclay, Alfred E.: The Digestive Tract. 1933, Cambridge, At the University Press.
3. Brosch, A.: Wien. M. Woch.; 1910, pg. 1144–1155, 1210–1214, 1276–1283.
4. Brown, Philip W.: G. Blumer’s The Therapeutics of Internal Diseases; 1943, 3rd Ed.; Vol. IV; Appleton Co.
5. Bryant, John: Am. J. M. Sc.; 167; 1924, 499.