1. Beckert: Arch. Augenhk.100, 285 (1929).
2. Cibis: Klin, Mbl. Augenhk.102, 824 (1939).
3. Drexel: Arch. Augenhk.92, 49 (1923).
4. Franceschetti: Handbuch Ophthalmologie. Bd. 1, S. 796. Berlin: Springer 1931.
5. Kawakami: Graefes Arch.116, 568 (1926).