Henry David Thoreau (2014). “Citizen Thoreau: Walden, Civil Disobedience, Life Without Principle, Slavery in Massachusetts, A Plea for Captain John Brown”, p.233, Graphic Arts Books
Stephen R. Covey (2015). “The Stephen R. Covey Interactive Reader - 4 Books in 1: The 7 Habits of Highly Effective People, First Things First, and the Best of the Most Renowned Leadership Teacher of our Time”, p.422, Mango Media Inc.
"Daniel J. Levitin Q&A: 'We've created more information in the past few years than in all of human history before us'". Interview with Lisa O'Kelly, www.theguardian.com. January 18, 2015.