  We study an inverse scattering problem of a perturbed biharmonic operator. we
show that the high-frequency asymptotic of scattering amplitude of the
biharmonic operator uniquely determine the curl A and {V -1/2 nablaA}. We also
study the near-field scattering problem and show that the high-frequency
asymptotic expansion up to a certain error in terms of frequency lambda
recovers the same two above quantities with no additional information about A
and V. We also prove stability estimates for curl A and {V -1/2 nablaA}.
