1. Nippon-gankagakkai Zasshi;ASAYAMA, I.;Trans. Amer. Acad. Ophthal. Otolaryng,1892
2. Trans;COLLINS, E.;TREACHER,1919
3. COVERDALE, H. V. (1929). British Journal of Ophthalmology, 13, 529.
4. Text-book of Ophthalmology;DANIEL, P.M.; DAWES, J.D.K.; PRICHARD, M.M.L.;Philos. Trans. roy. Soc,1953
5. DANIEL, P. M., DAWES, J. D. K., and PRICHARD, M. M. L. (1940b). Ibid., p. 2592.