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2. CROCKER, A. C. (1951). Ibid., 8, 573.
3. HASSENPFLUG, K. (1957). Derm. Wschr., 136, 1345.
4. HEDGES, C. C., Jr. (1959). Amer. J. Ophthal., 47, 683.
5. HELWIG, E. B. (1957). Proc. Pacific Coast Derm. Ass., pp. 25-28.