Henry David Thoreau (2014). “Citizen Thoreau: Walden, Civil Disobedience, Life Without Principle, Slavery in Massachusetts, A Plea for Captain John Brown”, p.61, Graphic Arts Books
Henry David Thoreau, Jeffrey S. Cramer (2007). “I to Myself: An Annotated Selection from the Journal of Henry D. Thoreau”, p.201, Yale University Press
Henry David Thoreau (2012). “The Green Thoreau: America's First Environmentalist on Technology, Possessions, Livelihood, and More”, p.72, New World Library
Henry David Thoreau (2012). “The Green Thoreau: America's First Environmentalist on Technology, Possessions, Livelihood, and More”, p.72, New World Library
Henry David Thoreau, Jeffrey S. Cramer (2007). “I to Myself: An Annotated Selection from the Journal of Henry D. Thoreau”, p.204, Yale University Press