On one approximation estimate

Linear operators satisfying some conditions are considered. The given operators are a particular kind of class $S_{2m}$ operators (by P. P. Korovkin). The estimate of the value $\left|L_n(f,x)-f(x)\right|$ for the $f \in W^2H^\alpha_M$ is received, $L_n$ belongs to the class $S_6$. For the estimate derivation the interpolation method is used, described in the works by Yu. G. Abakumov and O. N. Shestakova.