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We use the next-to-next-to-leading order (NNLO) contributions to
anomalous dimension governing the evolution of non-singlet quark
distributions. We use the $xF_3$ data of the CCFR collaboration
to obtain some unknown parameters which exist in the non-singlet
quark distributions in the NNLO approximation. In the fitting
procedure, Bernstein polynomial method is used. The results of
valence quark distributions in the NNLO, are in good agreement
with the available theoretical model.
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