1. Unpublished data;Chignell, A.H.,1974
2. Transactions of the Ophthalmological Societies of the;Chignell, A.H.;United Kingdom,1975
3. D. M. (1971). American Journal of Ophthalmology, 71, 835.
4. Hitchings, R. A., Levy, I. S., and Chignell, A. H. (1974).
5. British Journal of Ophthalmology, 58, 588.