1. Surgical anatomy of the anal canal with special reference to the surgical importance of the internal sphincter and conjoint longitudinal muscle;Morgan;Ann R Coll Surg Engl,1956
2. The length of the anal canal;Nivatvongs;Dis Colon Rectum,1981
3. The relationship of hemorrhoids to portal hypertension;Jacobs;Dis Colon Rectum,1980
4. Defecation and continence. Some new concepts;Scharli;Dis Colon Rectum,1970
5. Gray's Anatomy;Williams,1980