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
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
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
John Locke (1824). “The Works of John Locke: Essay concerning human understanding (concluded) Defence of Mr. Locke's opinion concerning personal identity. Of the conduct of the understanding. Some thoughts concerning reading and study for a gentlemen. Elements of natural philosophy. New method of a common-place-book”, p.356