The excellent agreement with experimental data has been achieved in fitting the resistivity of
doped manganate-ruthenates for whole temperature range. The analysis interpreted the resistivity in terms of
percolation of carriers through the system of grain boundaries, having been assumed as the conductive
fractal medium. The percolative conduction regime has been shown substantial for the K-doped ruthenates
[H.N. Nhat, H.D. Chinh and M.H. Phan, Solid State Commun. 139 (2006) 456], and we confirm here that
this approach also correctly discusses the unusual semiconductor-like behaviours of the doped manganateruthenates.
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