1. ASHTON, N., WARD, B., and SERPELL, G. (1954). Brit. J. Ophthal., 38, 397.
2. Text-book of Ophthalmology;DUKE-ELDER, S.,1938
3. LIEBITZKY, H. (1928). Klin. Mbl. Augenheilk., 81, 42.
4. Retinal Circulation in Man and Animals;MICHAELSON, I.C.,1954
5. Anatomie und Histologie des menschlichen Augapfels;SALZMANN, M.,1912