@proceedings{gruhler2010despite,
  title = {Despite all strategies for enhancing resource efficiency, per capita material stock is increasing - Housing stock and building material flows in Germany 2050}
  author = {Gruhler, Karin and Deilmann, Clemens},
  url = {Retrieved from: http://cesb.cz/cesb10/papers/3_materials/044.pdf},
  year = {2010}
}