^Ansbro, John J. (1982). Martin Luther King, Jr: The Making of a Mind. Orbis Books. pp. 146-7, 149.
^Huxley, Aldous and Baker Robert S.(ed.) (2002). Complete Essays, 1936-1938. Volume 4. I.R. Dee. pp. 240, 248.
See also the reference to Gregg's The Power of Non-Violence in Huxley's Ends and Means (1937).