@unpublished{SchulzeSeiler2008,
  author  = {Bert-Wolfgang Schulze and J{\"o}rg Seiler},
  title   = {The edge algebra structure of boundary value problems},
  institution = {Institut f{\"u}r Mathematik},
  series    = {Preprint},
  number    = {(2001) 11},
  year    = {2008},
}