Elbert Hubbard (2009). “Love, Life & Work: Being a Book of Opinions Reasonably Good-Natured Concerning How to Attain the Highest Happiness for One's Self with the Least Possible Harm to Others”, p.133, The Floating Press
James C. Humes, Benjamin Franklin (1995). “The wit and wisdom of Benjamin Franklin: a treasury of more than 900 quotations and anecdotes”, Harpercollins