1. Allen, C. W.: 1973,Astrophysical Quantities, The Athlone Press, University of London.
2. Arnett, W. D.: 1978,Astrophys. J. 219, 1008.
3. Batten, A. H., Fletcher, J. M., and Mann, P. I.: 1978,Publ. Dom. Astrophys. Obs. 15, 121.
4. Canavaggia, R.: 1980,Astron. Astrophys. 83, 105.
5. McCluskey, G. E. Jr. and Kondo, Y.: 1972,Astrophys. Space Sci. 17, 134.