1. BOLTON CARTER, J. F. (1951), Lancet, ii, 20.
2. BOLTON CARTER, J. F., MILNE, E. H., and WHITTET, T. D. (1952), Ibid., ii, 660.
3. FLETCHER, R. F. (1956), Ibid., i, 509.
4. HANDFIELD-JONES, R. P. C., and LEWIS, H. B. M. (1952), Ibid., i, 585.
5. HORVITZ, A., SACHAR, L. A., and ELMAN, R. (1943), J. Lab.