  The temperature dependences of the dc resistivity and the nonlinear transport
properties in pure, Rb-doped, and W-doped blue bronze K$_{0.3}$MoO$_{3}$ single
crystals are presented. In comparison with the Rb doping, the W doping has
larger effects on the electrical transport properties and the Peierls
transition. In particular, the maximum in the temperature dependence of the
threshold field for nonlinear transport, observed in pure and Rb-doped samples
around 100 K, is absent in W-doped K$_{0.3}$MoO$_{3}$. These results are
discussed with respect to the proposed incommensurate-commensurate transition
of the charge-density-wave and its interaction with impurities and normal
carriers.
