Demidenko G. V.
          Quasielliptic operators and Sobolev type equations
        We consider a class of matrix quasielliptic operators on the n-dimensional  space. For these operators, we establish the isomorphism properties in some  special scales of weighted Sobolev spaces. Basing on these properties, we prove  the unique solvability of the initial value problem for a class of Sobolev type  equations.