1. Mackenzie, Medic. Transactions of the college of Physicians IV, p. 56, 1813.
2. Parry, Collections from the unpublished Medical Writings, London 1823, p. 560.
3. Patouillet, Middlemore, Vol. II, p. 237.
4. Szokalski, Ueber die Empfindungen der Farben etc. Giessen, Académie des sciences 1842.
5. Mackenzie, A practical treatise on the diseases of the eye. 4. ed. London 1854, p. 932.