1. Abell, G.O., Corwin, H.G. and Olowin, R.P. 1989, Astrophys. J. Supplement, 70, 1
2. Aharonian, F.A., 2001, ”TeV blazars and cosmic infrared background radiation” in Proc. 27th ICRC, ed: R.Schlickeiser, Hamburg, 2001, Vol. Invited, Rapporteur, and Highlight Papers, pp.250–261
3. Atoyan, A.M. and Völk, H.J. 2000, Astrophys. J., 535, 45
4. Arabadjis, J.S. and Bregman, J.N. 1999, Astrophys. J., 514, 607
5. Berezinsky, V.S., Blasi, P. and Ptuskin, V.S. 1997, Astrophys. J., 487, 529