1. R. von Mises,Phys. Z. 19, 490 (1918).
2. M. Kendall and A. Stuart,The Advanced Theory of Statistics (Griffin, London, 1977), Vol. 1, 4th edn., Chapter 2.
3. M. G. Kendall and W. R. Buckland, eds.,A Dictionary of Statistical Terms (Oliver and Boyd, London, 1960), 2nd edn.; see article entitled ?Dispersion.?
4. G. Pólya,Ann. Inst. Henri Poincaré 1, 117 (1931).
5. P. Lévy,Bull. Soc. Math. France 67, 1 (1939).