1. Bacon, A. P. C., Froome, K., Gent, A. E., Cooke, T. K., and Sowerby, P., Lancet, i, 265 (1967).
2. Beattie, A. D., Dagg, J. H., Goldberg, A., Wang, I., and Ronald, J., Brit. Med. J., i, 488 (1972).
3. Beattie, A. D., Moore, M. R., Devenay, W. T., Millar, A. R., and Goldberg, A., Brit. Med. J., i, 491 (1972).
4. Burnet, J., History of the Water Supply to Glasgow (Bell and Bain, Glasgow, 1869).
5. Crawford, M. R., and Morris, J. N., Lancet, ii, 1087 (1967).