@unpublished{BachmannGraySchoenemann1997,
  author  = {Olaf Bachmann and S. Gray and Hans Sch{\"o}nemann},
  title   = {MP Prototype Specification},
  institution = {Fachbereich Mathematik},
  series    = {Reports on Computer Algebra (ZCA Report)},
  number    = {12},
  year    = {1997}
}