[en] We use the Vlasov equation plus the Planck's constant - corrections to describe collective nuclear vibrations in the small amplitude limit. Separable forces of the multipole - multipole type are employed to study the quadrupole and octupole resonances. Whereas the giant states exhibit the well known distortions of the Fermi sphere already at the classical level we find that the low lying 3^- state has an isotropic pressure tensor in the Planck's constant #-> # 0 limit. Quantum corrections reestablish a small distortion and thus a finite restoring force