1. Aronoff, A., Johnson, L., and Dworkin, S. (1960). Canad. med. Ass. J., 83, 58.
2. Ball, J. (1954). Ann. rheum. Dis., 13, 277.
3. Bywaters, E. G. L. (1957). Ibid., 16, 84.
4. Cruickshank, B. (1954). Ibid., 13, 136.
5. Edwards, E. A. (1960). Amer. J. Surg., 99, 837.