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2. HERBERT, H. (1927). Ibid., 47, 155.
3. LEHMANN, H. (1927). Z. Augenheilk., 62, 230.
4. LLOYD, R. I. (1930). Amer. J. Ophthal., 13, 753.
5. MALBRAN, J. (1937). Arch. Oftal. (B. Aires), 12, 85.