1. Tumors ventral to the sacrum;Whittaker;Am. Surgery,1938
2. Sacral and presacral tumors;Ross;Am. J. Surg.,1948
3. Retrorectal tumors;Jackman;J. A. M. A.,1951
4. Presacral tumors;Mayo,1953
5. Developmental cysts as a source of perianal abscesses, sinuses and fistulas;Hawkins;Am. J. Surg.,1953