Albert Einstein (2015). “Bite-Size Einstein: Quotations on Just About Everything from the Greatest Mind of the Twentieth Century”, p.32, St. Martin's Press
"The philosophy of Niels Bohr" by Aage Petersen in "Bulletin of the Atomic Scientists", Volume 19, No. 7 (September 1963), as quoted in Abraham Pais "The Genius of Science: A Portrait Gallery" (p. 24), 2000, and in Paul McEvoy "Niels Bohr: Reflections on Subject and Object" (p. 291), October 2000.
Quoted in Christian Monitor, and Religious Intelligencer, 4 July 1812. An almost identical quotation by Newton, said to have been uttered "a little before he died," appears in Joseph Spence, Anecdotes, Observations, and Characters of Books and Men, published in 1820 but extant in manuscript form from around 1730. A paraphrase of Newton's words was printed in a note in a 1797 edition of TheWorks of Alexander Pope.