@article{haberl2004ecological,
  title = {Ecological footprints and human appropriation of net primary production: A comparison}
  author = {Haberl, Helmut, Mathis Wackernagel, Fridolin Krausmann, Karl-Heinz Erb, Chad Monfreda},
  journal = {Land Use Policy},
  doi = {10.1016/j.landusepol.2003.10.008},
  year = {2004}
}