A. Tolón Becerra, X. Lastra Bravo, F. J. Piñero Contreras, and S. Fernández Montero, “European Union energy policy for sustainable development Nonlinear distribution proposed for EU’s 20-20-20 energy goals”, Obs. medioambient., vol. 14, pp. 255–276, Dec. 2011, doi: 10.5209/rev_OBMD.2011.v14.37312.