Lawrence A. Cunningham, Warren E. Buffett (2013). “The Essays of Warren Buffett: Lessons for Corporate America (Third Edition)”, p.71, Carolina Academic Press
"The Security I Like Best". Warren Buffett, The Commercial and Financial Chronicle (December 6, 1951), as quoted in "5 Tips From Warren Buffett Every Investor Should Take to Heart" by Stacy Rapacon, grow.acorns.com. August 24, 2017.