1. Shone, M. G. T., Agric. Res. Counc. Radiobiol. Lab., ARCRL, 12, 47 (September 1964).
2. Schulz, R. K., Health Phys., 11, 1317 (1965).
3. Mercer, E. R., and Ellis, F. B., Agric. Res. Counc. Radiobiol. Lab., ARCRL, 12, 49 (September 1964).
4. Squire, H. M., Agric. Res. Counc. Radiobiol. Lab., ARCRL, 8, 64 (September 1962).
5. Menzel, R. G., Health Phys., 11, 1325 (1965).