Heng K., D. Lazzati, R. Perna, P. Garnavich, A. Noriega-Crespo, D. Bersier, T. Matheson, and M. Pahre, The Astrophysical Journal 681, 1116-1122 (2008).
Forman W., C. Jones, E. Churazov, M. Markevitch, P. Nulsen, A. Vikhlinin, M.C. Begelman, H. Bohringer, J. Eilek, S. Heinz, and R.P. Kraft, The Astrophysical Journal 665, 1057-1066 (2007).
and 
