1. See, for example, Curtis, W. E., Dickens, F., and Evans, S. F., NATURE, 138, 63 (1936).
2. Szymanowski, W. T., and Hicks, R. A., J. Infect. Dis., 50, 1 (1932).
3. Hicks, R. A., and Szymanowski, W. T., J. Infect. Dis., 50, 466 (1932).
4. Krasny-Ergen, W., Radiologica, 1, 136 (1937).
5. Bateman, J. B., and Rosenberg, H., Report of the Intern. Congr. for Short Waves, Vienna, 1937, p. 129. There are some misprints in the numerical values.