@Book{noauthororeditor1986funktion,
  author = {Frey, Hans Dieter and Henning, Peter and Langer, Ewald and Wagner, Gitta and Weigner, Christiane},
  title  = {Bau und Funktion der Niederen Pflanzen (Algen, Moose, Farne)},

  year   = {1988},
  number = {},
  url    = {http://www.fachportal-paedagogik.de/fis_bildung/suche/fis_set.html?FId=544320},

  const  = {\ text}
}