@article{mark2006the,
  title = {The ecological sustainability of regional metabolisms: Material flow analyses of the regions of Hamburg, Vienna and Leipzig}
  author = {Mark Hammer, Stefan Giljum, Fred Luks, Matthias Winkler},
  journal = {Natur und Kultur (Nature and Culture)},
  url = {http://www.umweltethik.at/wp/wp-content/uploads/HammerEtAlRegionaleMetabolismen.pdf},
  year = {2006}
}