1. E. T. Whittaker:History of the Theories of Ether and Electricity, Vol.2, Chap. II (London, 1953), p. 27.
2. E. T. Whittaker:From Euclid to Eddington (New York, N. Y., 1958), p. 96.
3. L. D. Landau andE. M. Lifshitz:Fluid Mechanics (London, 1959), p. 259.
4. L. Rongved:Nuovo Cimento,44 B, 355 (1966).