Cancer of the gastrointestinal tract :
part two (colon, rectum, anus).

APA Citation

American Cancer Society. (1975). Cancer of the gastrointestinal tract: part two (colon, rectum, anus). New York: American Cancer Society.

MLA Citation

American Cancer Society. Cancer of the Gastrointestinal Tract: Part Two (colon, Rectum, Anus). New York: American Cancer Society, 1975.

Warning: These citations may not always be complete (especially for serials).