1. BAME, S. J., CONNER, J. P., BRUMLEY, F. D., HOSTETTER, R. L., and GREEN, A. C.: 1963, J. Geophys. Res. 68, 1221.
2. BATES,D.R. and DALGARNO,A.:1953,Proc. Phys. Soc. (Lond.)A66,972.
3. BROWN, W. L., DAVIDSON, L. W., and MEDFORD, L. V.: 1964, Bell Lab. Rec.
4. CAMERINI,V.:1952,Progress in Cosmic Ray Physics (Ed. by J.G. WILSON),North-Holland Publ. Co.,Amsterdam,Vol. 1,p.3
5. CORNWALL, J. M., SIMS, A. R., and WHITE, R. S.: 1965, J. Geophys. Res. 70, 3099.