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.9, Harvard University Press
Percy Bysshe Shelley, Mary Wollstonecraft Shelley (1840). “A defence of poetry. Essay on the literature, arts, and manners of the Athenians. Preface to the Banquet of Plato. The banquet”, p.28