1. M. Bayet, J. L. Delcrox andJ. F. Denisse:Journ. Phys. Radium,15, 795 (1954);16, 274 (1955);17, 923 (1956).
2. I. B. Bernstein:Discharge Theory, Lecture Notes for the Summer Institute in Plasma Physics, Princeton University (1962); see also:I. M. Cohen:Theory of Spherical Electrostatic Probes in a Slightly Ionized, Collision-Dominated Gas, Princeton University, Plasma Physics Laboratory, Report MATT-180 (1963).
3. S. Chapman andT. G. Cowling:The Mathematical Theory of Non-Uniform Gases (Cambridge, 1960).
4. J. Naze:Compt. Rend.,251, 651, 854, 2284 (1960).
5. G. Sansone:Orthogonal Functions (New York, 1959).