@misc{Kummer2000,
  author    = {Kummer, Volker},
  title     = {Litterski, B., Pflanzengeographische und {\"o}kologische Bewertung der Flechtenflora Mecklenburg-Vorpommerns; Berlin, Cramer, 1999},
  year      = {2000},
  language  = {de}
}
@misc{Micheel2000,
  author    = {Micheel, Burkhard},
  title     = {Stichworte zu Thema Immunologie},
  year      = {2000},
  language  = {de}
}
@misc{Micheel1999,
  author    = {Micheel, Burkhard},
  title     = {Stichworte zu Thema Immunologie},
  year      = {1999},
  language  = {de}
}