[en] The appearance of 'overlap-knock-out resonances' was first observed in the ISR. These resonances caused severe enlargement of the vertical beam dimensions and a significant reduction in the luminosity. Somewhat later these resonances were also observed with bunched beams of different energies in each ring, and under resonant conditions reduced the beam lifetime to a few seconds with a beam-beam tune shift of less than 10^-5. For the case of the SSC where the energies of the beams may under certain circumstances be unequal, these resonances may appear and cause beam loss