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2. CIRNCIONE, G. (1903). Beitr. Augenheilk., 6, 312 (Heft 55, p. 4).
3. DUVERGER, J., and REDSLOB, E. (1922). Arch. Ophtal., 39, 230.
4. STRAETEN, VAN DER, and DuYSE, D. VAN (1924). Ibid., 41, 257.
5. VERMEs (1906). Z. Augenheilk., 16, 64.