  In this Letter we point out that redshift surveys can break the degeneracy
between the galaxy bias, the power spectrum normalization, \sigma_{8,0} and the
growth factor, without the need for external information by using a simple and
rather general parametrization for the growth rate, the well known
\gamma-parametrization and measuring the power spectrum at least at two
different redshifts. We find that in next-generation surveys like Euclid,
\sigma_{8,0} and \gamma can be measured to within 1% and 5%, respectively,
while the bias b(z) can be measured to within 1-2% in each of 14 equal-width
redshift bins spanning 0.7<=z<=2.
