Albert Einstein (2015). “Bite-Size Einstein: Quotations on Just About Everything from the Greatest Mind of the Twentieth Century”, p.15, St. Martin's Press
Henry Beston, Elizabeth Jane Coatsworth (2001). “The Best of Beston: A Selection from the Natural World of Henry Beston from Cape Cod to the St. Lawrence”, p.18, David R. Godine Publisher
Henry Beston, Elizabeth Jane Coatsworth (2001). “The Best of Beston: A Selection from the Natural World of Henry Beston from Cape Cod to the St. Lawrence”, p.18, David R. Godine Publisher
Albert Einstein (2015). “Bite-Size Einstein: Quotations on Just About Everything from the Greatest Mind of the Twentieth Century”, p.15, St. Martin's Press