Variations of the TeV energy spectrum at different flux levels of Mkn 421 observed with the HEGRA system of Cherenkov telescopes

F. Aharonian, A. Akhperjanian, M. Beilicke, K. Bernlohr, H. Borst, H. Bojahr, O. Bolz, T. Coarasa, J. Contreras, J. Cortina, L. Costamante, S. Denninghoff, V. Fonseca, M. Girma, N. Gotting, G. Heinzelmann, G. Hermann, A. Heusler, W. Hofmann, D. Horns, I. Jung, R. Kankanyan, M. Kestel, J. Kettler, A. Kohnle, A. Konopelko, H. Kornmeyer, D. Kranich, H. Krawczynski, H. Lampeitl, M. Lopez, E. Lorenz, F. Lucarelli, O. Mang, H. Meyer, R. Mirzoyan, M. Milite, A. Moralejo, E. Ona, M. Panter, A. Plyasheshnikov, G. Puhlhofer, G. Rauterberg, R. Reyes, W. Rhode, J. Ripken, G. Rowell, V. Sahakian, M. Samorski, M. Schilling, M. Siems, D. Sobzynska, W. Stamm, M. Tluczykont, H.J. Volk, C. A. Wiedner, W. Wittek and R. A. Remillard

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