In a series of papers it was discussed,on the basis of phenomenological arguments, whether the high frequency quasiperiodic oscillations (kHz QPOs)observed in the neutron-star and black-hole X-ray sources originate in the same physical mechanism. Recently it was suggested that a general trend seen in neutron star kHz QPOs instead excludes such a uniform origin. Using the example of the atoll source 4U 1636-53 we illustrate that this is not neccesarily true.
 W. Kluźniak and M.A. Abramowicz: “Strong-Field Gravity and Orbital Resonance in Black Holes and Neutron Stars - kHz Quasi-Periodic Oscillations (QPO)”, Phys. Rev. Lett. (submitted), 2000; see also Acta Phys. Pol. B Vol. 32 (2001), pp. 3605–3612.
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