  A review of the author's results is given. Inversion formulas and stability
estimates for the solutions to 3D inverse scattering problems with fixed-energy
data are obtained. Inversions of exact and noisy data are stidied. The inverse
potential scattering problem is discussed in detail, inversion formulas are
derived and error estimates are obtained. Inverse obstacle scattering problem
with data at a fixed frequency is studied. Uniqueness theorems and stability
estimates are obtained.
  Inverse geophysical scattering problem is discussed. An algorithm for
computing the Dirichlet-to-Neumann map from the scattering amplitude and vicxe
versa is obtained. An analytical example of non-uniqueness of the solution to a
3D inverse geophysical problem is constructed. An inverse problem for a
parabolic equation is discussed.
