Koestler, Arthur (1964). Act of Creation. London: Hutchinson. pp. 265–266.
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National Education Association (1894). Report of the Committee of Ten on Secondary School Studies With The Reports of the Conferences Arranged by The Committee. New York: The American Book Company Read the Book Online
Layton, D. (1981). «The schooling of science in England, 1854–1939». En MacLeod, R.M.; Collins, P.D.B., eds. The parliament of science. Northwood, England: Science Reviews. pp. 188-210. ISBN0905927664. OCLC8172024.