1 N.. Arav, K.T. Korista, M.. de Kool, V.T. Junkkarinen, and M.C. Begelman, The Astrophysical Journal 516, (1999).
1 G.S. Burks, F.. Bartko, J.M. Shull, J.T. Stocke, E.R. Sachs, M.. Burbidge, R.D. Cohen, V.T. Junkkarinen, R.J. Harms, and D.. Massa, The Astrophysical Journal 437, (1994).