"Gaither's Dictionary of Scientific Quotations" edited by Carl C. Gaither, Alma E. Cavazos-Gaither, Springer Science & Business Media, (p. 1785), January 5, 2012.
Aaron Siskind, Maricia Battle, Ann Banks, Federal Writers' Project, National Museum of American Art (U.S.) (1990). “Harlem photographs, 1932-1940”, Smithsonian Inst Pr
United States. President (1945-1953 : Truman), Harry S. Truman (1966). “Harry S. Truman: Containing the Public Messages, Speeches, and Statements of the President, 1945-53”