RENE DESCARTES (1952). “RULES FOR THE DIRECTION OF THE MIND DISCOURSE ON THE METHOD MEDITATIONS ON FIRST PHILOSOPHY OBJECTIONS AGAINST THE MEDITATIONS AND REPLIES THE GEOMETRY”
Albert Einstein (2015). “Bite-Size Einstein: Quotations on Just About Everything from the Greatest Mind of the Twentieth Century”, p.52, St. Martin's Press
John von Neumann's remarks as keynote speaker at the first national meeting of the Association for Computing Machinery (1947) as quoted in "Archaeology of computers: Reminiscences, 1945-1947" by Franz L. Alt, Communications of the ACM, Volume 15, Issue 7, special issue: Twenty-fifth anniversary of the Association for Computing Machinery (p. 694), July 1972.
Albert Einstein (2015). “Bite-Size Einstein: Quotations on Just About Everything from the Greatest Mind of the Twentieth Century”, p.31, St. Martin's Press