@unpublished{EnglRoesch1991,
  author  = {Gabriele Engl and Ronald R{\"o}sch},
  title   = {Studien zum Programmsystem PROMO},
  institution = {Fachbereich Mathematik},
  series    = {Berichte der Arbeitsgruppe Technomathematik (AGTM Report)},
  number    = {58},
  year    = {1991},
  url  = {http://nbn-resolving.de/urn:nbn:de:hbz:386-kluedo-6625},
}