1. Schirmer.-Arch. f. Ophthal, Vol. VII, p. 119, 1860.
2. Sturge.-l'rans. Clinical Soc., Vol. XII, p 162, 1879.
3. Horrocks.-Trans. Ophthal. Soc. U.K., Vol. III,, p. 106, 1883.
4. Milles.-Traits Ofhthal. Soc. U.K., Vol. IV, p. 168, 1884. 5 Lawford.-Trans. Obhthal. Soc. U.K., Vol. V, p. 136. 1885.
5. Galezowski.-Ann. de Derm. et Syhh., Vol. IX, p. 242, 1898.