  We investigate the asymptotic behavior of solutions to semi-classical
Schroedinger equations with nonlinearities of Hartree type. For a weakly
nonlinear scaling, we show the validity of an asymptotic superposition
principle for slowly modulated highly oscillatory pulses. The result is based
on a high-frequency averaging effect due to the nonlocal nature of the Hartree
potential, which inhibits the creation of new resonant waves. In the proof we
make use of the framework of Wiener algebras.
