Martin Dugard (2011). “To Be a Runner: How Racing Up Mountains, Running with the Bulls, or Just Taking On a 5-K Makes You a Better Person (and the World a Better Place)”, p.7, Rodale
Henry David Thoreau (2014). “Citizen Thoreau: Walden, Civil Disobedience, Life Without Principle, Slavery in Massachusetts, A Plea for Captain John Brown”, p.68, Graphic Arts Books