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
James Boswell, Samuel Johnson (1799). “Boswell's Life of Johnson: Including Boswell's Journal of a Tour of the Hebrides, and Johnson's Diary of A Journey Into North Wales”, p.103