Georg Wilhelm Friedrich Hegel, Arnold V. Miller (1970). “Hegel's Philosophy of Nature: Being Part Two of the Encyclopedia of the Philosophical Sciences (1830), Translated from Nicolin and Pöggeler's Edition (1959), and from the Zusätze in Michelet's Text (1847)”, p.371, Oxford University Press
Georg Wilhelm Friedrich Hegel, Hugh Barr Nisbet, Duncan Forbes (1975). “Lectures on the Philosophy of World History”, p.171, Cambridge University Press