Tilted Rotation and Wobbling Motion in Nuclei
  The self-consistent harmonic oscillator model including the three-dimensional cranking term is extended to describe collective excitations in the random phase approximation. It is found that quadrupole collective excitations associated with wobbling motion in rotating nuclei lead to the appearance of two- or three-dimensional rotation. 
W.D. Heiss and R.G. Nazmitdinov