1. Brennand, R., and Bunker, N. V. (1960). Lancet, 1, 578.
2. Elliott, W., Horn, D. B., Kerr, D. N. S., and Pearson, D. T. (1961). Ibid, 1, 248.
3. Jackson, R. C., Bunker, N. V. D., Elder, W. J., and Joekes, A. M. (1960). Brit. med. J., 2, 1909.
4. Micro-analysis in Medical;King, E.J.; Wootton, I.D.P.,1956
5. Merrill, J. P. (Quoted by Mather, J., 1960). Trans. Amer. Soc. artif.