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
Scott Adams (2007). “Stick to Drawing Comics, Monkey Brain!: Cartoonist Explains Cloning, Blouse Monsters, Voting Machines, Romance, Monkey G ods, How to Avoid Being Mistaken for a Rodent, and More”, p.438, Penguin
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.31, St. Martin's Press