T. S. Eliot (1986). “The Use of Poetry and the Use of Criticism: Studies in the Relation of Criticism to Poetry in England”, p.111, Harvard University Press
Ralph Waldo Emerson, Robert Ernest Spiller, Alfred Riggs Ferguson, Joseph Slater, Jean Ferguson Carr (1971). “The Collected Works of Ralph Waldo Emerson: Nature, addresses, and lectures”, p.58, Harvard University Press