  The spin-1/2 Heisenberg model on an anisotropic triangular lattice is
considered in the mean-field RVB approximation. The analytical estimates for
the critical temperatures of the longitudinal s-RVB state (the upper one) and
the 2D s-RVB state (the lower one) are obtained which fairly agree with the
results of the previous numerical studies on this system. Analytical formulae
for the magnetic susceptibility and the magnetic contribution to the specific
heat capacity in the longitudinal s-RVB state are obtained which fairly
reproduce the results of the numerical experiment concerning these physical
quantities.
