@unpublished{Shlapunov2008,
  author  = {Alexander Shlapunov},
  title   = {Iterations of self-adjoint operators and their applications to elliptic systems},
  institution = {Institut f{\"u}r Mathematik},
  series    = {Preprint},
  number    = {(1999) 03},
  year    = {2008},
}