1. Arnaud, K., Li Ti pei, Riley, P.A., Wolfendale, A.W., Dame, T.M., Brock, J.E., and Thaddeus, P. 1982, M.N.R.A.S., 201, 745.
2. Axford, W.I., Leer, E., and Skandron, K.G. 1977, Proc. 15th Int. Cosmic Ray Conf.
y
1, 132.
3. Bell, A.R. 1978, M.N.R.A.S., 182, 147.
4. Beuermann, K., Kanbach, G., and Berkhuijsen, E.M. 1985, Astr. Ap., 153, 17.
5. Bhat, C.L., Issa, M.R., Houston, B.P., Mayer, C.J., and Wolfendale, A.W. 1985, Nature, 314, 511.