1. CROSS, A. G. (1941). Lancet, 2, 515.
2. DREW, A. L. (1954). Neurology (Minneap.), 4, 449.
3. Text-book of Ophthalmology;DUKE-ELDER, S.,1940
4. External Infections of the Eye;FEDUKOWICZ, H.B.,1963
5. Principles of Internal Medicine;HARRISON, T.R.,1954