Albert Einstein
Albert Einstein, conversation with Heinrich Zangger (1918)

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  • Albert Einstein to Heinrich Zangger, ca. August 1918. CPAE, Vol. 8, Doc. 597
  • As quoted in Albert Einstein; Alice Calaprice; Freeman Dyson (14 July 2011). The Ultimate Quotable Einstein. Princeton University Press. p. 5. ISBN 978-0-691-13817-6. Retrieved 30 December 2011.