@article{FischerLienertSchnelleretal.2002,
  author    = {Fischer, Markus and Lienert, J. and Schneller, J. and Diemer, M.},
  title     = {Local extinctions of the wetland specialist Swertia perennis : a revistation study based on herbarium records},
  year      = {2002},
  language  = {en}
}