  The momentum-space bosonization method is extended to the case of a
Nambu--Jona-Lasinio type model with vector and axial-vector mesons. The method
presented gives the possibility of deriving any meson vertex function to all
orders in momenta and to the leading order in $1/N_c$. Two-point functions,
which describe one-particle transitions to the hadronic vacuum, and meson
self-energies are considered. We find new relations which generalize the
well-known KSFR relation and both the first and the second Weinberg sum rules.
These result from a consistent treatment of higher order terms in the momentum
expansion.
