1. Buie, L. A.. Practical Proctology. Ed. 1, Philadelphia, W. B. Saunders Company, 1937, p. 119.
2. Dunphy, J. E.: Surgical anatomy of the anal canal. Arch. Surg.57: 791, 1948.
3. Eisenhammer, S.: The surgical correction of chronic internal anal (sphincteric) contracture. S. Afr. Med. J.25: 486, 1951.
4. Gabriel, W. B.: The Principles and Practice of Rectal Surgery. Ed. 5, Springfield, Charles C Thomas, 1963, p. 290.
5. Lockhart-Mummery, L. P., and O. V. Lloyd-Davies. The operative treatment of fibrous stricture of the rectum: With the description of a new technique. Brit. J. Surg.23: 19, 1935.