Discovery of a flux-related change of the cyclotron line energy in Hercules X-1R. Staubert, N. I. Shakura, K. Postnov, J. Wilms, R. E. Rothschild, W. Coburn, L. Rodina and D. KlochkovA&A, 465 2 (2007) L25-L28DOI: https://doi.org/10.1051/0004-6361:20077098
