1. Andrén, L., S. Freiberg and S. Welin: Roentgen diagnosis of small polyps in the colon and rectum. Acta radiol.43: 201, 1955.
2. Blatt, L. J.: Polyps of the colon and rectum: Incidence and distribution. Dis. Colon & Rectum.4: 277, 1961.
3. Catanzaro, F. P. and A. Merlino: Adenomatous polyps of the gastro-intestinal tract. Rhode Island M. J.40: 333, 1957.
4. Enquist, I. F.: The incidence and significance of polyps of the colon and rectum. Surgery.42: 681, 1957.
5. Feyrter, F.: Zur Geschwulstlehre (nach Untersuchungen am menschlichen Darm.). I. Polypen und Krebs. Beitr. path. Anat.86: 663, 1931.