  A method based on the consistent use of the Green function formalism has been
developed to calculate the distribution of the single-particle strength in odd
nuclei with pairing. The method takes into account the quasiparticle-phonon
interaction, ground state correlations and a "refinement" of phenomenological
single-particle energies and pairing gap values from the quasiparticle-phonon
interaction under consideration. The calculations for 121Sn and 119Sn that were
performed in the quasiparticle$\otimes$phonon approximation, have shown a
reasonable agreement with experiment. The ground state correlations play a
noticeable role and mostly improve the agreement with experiment or shift the
results to the right direction.
