John Stuart Mill (2008). “Utilitarianism and On Liberty: Including 'Essay on Bentham' and Selections from the Writings of Jeremy Bentham and John Austin”, p.67, John Wiley & Sons
John D. Rockefeller (2015). “John D. Rockefeller on Making Money: Advice and Words of Wisdom on Building and Sharing Wealth”, p.7, Skyhorse Publishing, Inc.
Neil Armstrong's letter to the children of Troy, Michigan on the opening of its Public Library (1971), as quoted in "Why Libraries Matter: Letters to the Children of Troy, Michigan (From 1971)" by Lucas Reilly on Mental Floss, July 3, 2012.