@techreport{hammer2003material,
  title = {Material flow analysis on the regional level: questions, problems, solutions. NEDS Working Paper. No. 2}
  author = {Hammer, Mark; Giljum, Stefan; Bargigli, Silvia; Hinterberger, Friedrich},
  url = {http://seri.at/wp-content/uploads/2009/09/Material-flow-analysis-on-the-regional-level1.pdf},
  year = {2003}
}