https://www.bancaditalia.it/media/approfondimenti/2019/pop-bari/approfondimenti-popBari.pdf
https://www.fraserinstitute.org/sites/default/files/canada-us-energy-sector-competitiveness-survey-2023.pdf
https://www.cesifo-group.de/DocDL/ifoDD_18-01_29-31_Achten.pdf
https://www.linkiesta.it/2020/05/macron-merkel-piano-iniziativa-500-miliardi/