  The exact results for thermodynamical properties of one-dimensional spin-1/2
isotropic XY model with Dzyaloshinskii-Moriya interaction in random lorentzian
transverse field are obtained. This permits to discuss some approximate methods
of disordered spin systems theory. The approximate scheme of examining the
thermodynamics of one-dimensional spin-1/2 XXZ Heisenberg model with
Dzyaloshinskii-Moriya interaction in random lorentzian field is suggested.
