@book{97,
  author = {Hill Mark O and Mountford J O. and Roy D. B. and Bunce R. G. H.},
  title = {Ellenberg's indicator values for British plants. ECOFACT Volume 2 Technical Annex},
  year = {1999},
  volume = {2},
  month = {1999},
  publisher = {Institute of Terrestrial Ecology},
  url = {http://nora.nerc.ac.uk/6411/1/ECOFACT2a.pdf},
  language = {eng},
}