1. Allison, P. R. (1951). Surg. Obstet. Gynec., 92, 419.
2. An Introduction to Gastro-enterology;Alvarez, W.C.,1950
3. Secretory Mechanism of the Digestive Glands;Babkin, B.P.,1950
4. Bensley, R. R. (1902). Amer. J. Anat., 21, 105.
5. Berger, E. H. (1934). Ibid., 54, 87.