1. Brit;ARNOTT, E.J.; CRAWFURD, M.D.A.; TOGHILL, P.j;J. Ophthal,1966
2. System of Ophthalmology;DUKE-ELDER, S.,1964
3. Kimpton, London (1969) Ibid., vol. I I, p. 6o
4. Amer;EHRLICH, L.H.;J. Ophthal; Folia ophthal,1946
5. Arch;GREGG, J.B.; BECKER, S.F.;Ophthal. (Chicago); Docum. ophthal,1963