  We study WW and WZ production with $l\nu q{q}$ ($l=e,\mu$) final states using
data collected by the D0 detector at the Fermilab Tevatron Collider
corresponding to 4.3 fb^-1 of integrated luminosity from p-pbar collisions at
sqrt{s}=1.96 TeV. Assuming the ratio between the production cross sections
$\sigma(WW)$ and $\sigma(WZ)$ as predicted by the standard model, we measure
the total WV (V=W,Z) cross section to be $\sigma(WV)= 19.6^{+3.2}_{-3.0}$ pb,
and reject the background-only hypothesis at a level of 7.9 standard
deviations. We also use b-jet discrimination to separate the WZ component from
the dominant WW component. Simultaneously fitting WW and WZ contributions, we
measure $\sigma(WW) = 15.9^{+3.7}_{-3.2}$ pb and $\sigma(WZ) =
3.3^{+4.1}_{-3.3}$ pb, which is consistent with the standard model predictions.
