Dr. Robert C. Worstell, Dorothea Brande, Eark Nightingale, Claude M. Bristol, Napoleon Hill (2017). “Mindset StackingTM Inspirational Journal VolumeSS02”, p.6, Lulu.com
"Incredible Quotations: 230 Thought-Provoking Quotes with Prompts to Spark Students' Writing, Thinking, and Discussion". Book by Jacqueline Sweeney, 1997.
Booker T. Washington (1901). “An Autobiography: The Story of My Life and Work, the Original Brought Up-to-date with Over Half a Hundred Full Page Photo and Halftone Engravings and Drawings by Frank Beard”
Address at the Sorbonne, Paris, 23 Apr. 1910. Richard M. Nixon quoted this passage in his address to the nation announcing his decision to resign the presidency, 8 Aug. 1974. See Theodore Roosevelt 1; Theodore Roosevelt 2; Theodore Roosevelt 5