* [http://www.umweltbuero.at/feasiblefutures/wp-content/uploads/Progress%20Report%201_Feasible%20Futures_Zittel_final_14032012_WZ.pdf הערכה של זמינות דלקים] Feasible Futures for the Common Good, 2012 | * [http://www.umweltbuero.at/feasiblefutures/wp-content/uploads/Progress%20Report%201_Feasible%20Futures_Zittel_final_14032012_WZ.pdf הערכה של זמינות דלקים] Feasible Futures for the Common Good, 2012 |