1. BOCK, J. (1941). Klin. Mbl. Augenheilk., 107, 97.
2. BURKI, E. (1946). Ophthalmologica (Basel), 111, 134.
3. FRAN4OIS, J. (1957). Bull. Soc. belge Ophtal., No. 118.
4. GIFFORD, S. R. (1932). Arch. Ophthal. (Chicago), 7, 18.
5. KORNZWEIG, A. L. (1964). J. ped. Ophthal., 1, 51.