1. Adams, J.H., et al.: 1991, Astrophys. J. 375, L45.
2. Adams, J. H., and Leising, M.D.: 1991 , Proc 22nd Int. Cosmic Ray Conf. , 3, 304.
3. Anders, E., and Grevesse, N.: 1988, Geochim. Cosmochim. Acta 53, 197.
4. Baker, D.N., Mason, G.M. ,Figueroa, O., Colon, G., Watzin, J.G., and Aleman, R.M.: 1993, IEEE Trans. Geosci. Remote Sensing 31, 531.
5. Bertaux, J.L., and Blamont, J.E.: 1971 , Astron. Astrophys. 11, 200.