1. Bacon, H. E.: Anus, Rectum, Sigmoid Colon. Ed. 3. Philadelphia, J. B. Lippincott Company, 1949, 1127 pp.
2. Ball, T. L.: Cryoconization of the cervix for dysplasia and in-situ carcinoma. (In press.)
3. Cooper, I. S., and A. St. J. Lee: Cryostatic congelation: A system for producing a limited, controlled region of cooling or freezing of biologic tissues. J. Nerv. Ment. Dis.133: 259, 1961.
4. Englebardt, S. L.: Cryosurgery: Cold approach to hot cases. Modern Hosp.108: 140, 1967.
5. Goligher, J. C.: Surgery of the Anus, Rectum and Colon. Ed. 2. Springfield, Charles C Thomas, 1967, 1110 pp.