@unpublished{SchulzeVolpato2008,
  author  = {Bert-Wolfgang Schulze and A. Volpato},
  title   = {Green operators in the edge calculus},
  institution = {Institut f{\"u}r Mathematik},
  series    = {Preprint},
  number    = {(2004) 25},
  year    = {2008},
}