@unpublished{SavinSternin2009,
  author  = {Anton Savin and Boris Sternin},
  title   = {Pseudodifferential subspaces and their applications in elliptic theory},
  institution = {Institut f{\"u}r Mathematik},
  series    = {Preprint},
  number    = {(2005) 17},
  year    = {2009},
}