1. Rutherford, Chadwick and Ellis, "Radiations from Radioactive Substances" (Camb. Univ. Press, 1930), 172.
2. Bortkewitsch, quoted by Pearson, K., "Tables for Statisticians", (Cambridge University Press, 1914), lxxvii.
3. Nature, 148, 598 (1941).
4. Wright, Q., "A Study of War" (University of Chicago Press, 1942), appendix xx.