Dr. Robert C. Worstell, Dorothea Brande, Claude M. Bristol, Earl Nightingale, Napoleon Hill (2017). “Mindset StackingTM Inspirational Journal VolumeSS01”, p.16, Lulu.com
Meriwether Lewis, William Clark, Thomas Rees (2010). “Travels to the Source of the Missouri River: And Across the American Continent to the Pacific Ocean 1804, 1805, and 1806”, p.213, Cambridge University Press
Samuel Johnson (1787). “The Works of Samuel Johnson, LL.D.: Together with His Life, and Notes on His Lives of the Poets, by Sir John Hawkins, Knt. In Eleven Volumes ...”, p.156
Joseph Addison (1856). “The works of Joseph Addison: including the whole contents of B. Hurd's edition, with letters and other pieces not found in any previous collection, and Macaulay's essay on his life and works”, p.428