1. Antoniadi, E. M. 1974, The Planet Mercury, transl. Patrick Moore (Shaldon: Keith Reid), p. 10
2. Caesar, De Bello Gallico, 6.17
3. Tacitus, Germania, 9
4. Heath, Thomas L. 1932, Greek Astronomy (London: J. M. Dent), pp. xv, xxvi and xxviii
5. Krupp, E. C. 1979, ’Astronomers, pyramids and priests’ in In Search of Ancient Astronomies, ed. E. C. Krupp (London: Chatto & Windus), p. 198