Variable pulse profiles of Hercules X-1 repeating with the same irregular 35 d clock as the turn-onsR. Staubert, D. Klochkov, D. Vasco, K. Postnov, N. Shakura, J. Wilms and R. E. RothschildA&A, 550 (2013) A110DOI: https://doi.org/10.1051/0004-6361/201220316
