1. Bmo, 1. (1951). Ophthalmologica (Basel), 121, 201.
2. CALLANDER, C. L. (1920). Ann. Surg., 71, 428.
3. CASHELL, G. T. W. (1948). Trans. ophthal. Soc. U.K., 68, 245.
4. CLARK, E. R. (1938). Physiol. Rev., 18, 229.
5. Text-Book of Ophthalmology;DUKE-ELDER, S.,1940