Point-contact spectra of $2H-NbS{{e}_{2}}$ in the superconducting state
  A qualitative study of the electron-phonon interaction (EPI) spectra in $2H-NbS{{e}_{2}}$ is carried out by the method of point-contact spectroscopy in the superconducting state. Anisotropy of the EPI spectra for contacts oriented in the principal crystallographic directions (along the $c$ axis and parallel to the basal surface) was observed. Approximate values of the positions of the main features in the phonon density of states were established for both directions. The additional low-frequency peaks observed in the spectra for separate crystallographic orientations are associated with the collective oscillations of the amplitude and phase of charge density waves. 
N.L. Bobrov, L.F. Rybal'chenko, M.A. Obolenskii, and V.V. Fisun
cond-mat.supr-con