X-ray QPOs in Black-Hole Binary Systems
  We briefly review the properties and physical consequences of quasiperiodic oscillations (QPOs) seen on many occasions in the X-ray emission from black-hole binary systems. We also report on the discovery of QPOs at 164 and 328 Hz in GRS1915+105. These appear to be analogous to the harmonic systems of high-frequency QPOs seen in XTEJ1550-564 and GROJ1655-40. 
Ronald A. Remillard, Michael P. Muno (MIT), Jeffrey E. McClintock   (CFA), and Jerome A. Orosz (Utrecht U.)