1. FRANCESCHEmTI, A. (1927). Klin. Mbl. Augenheilk, 79, 482.
2. LAW, F. W. (1943). Trans. ophthal. Soc. U.K., 63, 295.
3. MICHAIL, D. (1932). Arch. Ophtal., 49, 384.
4. SPINELLI, F. (1937). Arch. Ottal., 44, 89.
5. TARTUFERI (1902). Ann. Ottal., 31, 545.