
Commenting on the 'Negro Project' in a letter to Dr. Clarence Gamble, December 10, 1939. http://smithlibraries.org/digital/items/show/495 - Sanger manuscripts, Sophia Smith Collection, Smith College, Northampton, Massachusetts. Also described in Linda Gordon's Woman's Body, Woman's Right: A Social History of Birth Control in America. New York: Grossman Publishers, 1976.
(Note: There is a different date circulated, e.g. Oct. 19, 1939; but Dec. 10 is the correct date of Mrs. Sanger's letter to Mr. Gamble.)