http://library.fes.de/pdf-files/wiso/14397.pdf
http://cep.lse.ac.uk/pubs/download/special/cepsp34.pdf
https://www.bancaditalia.it/compiti/riserve-portafoglio-rischi/cis/Presentazione_CIS_5.07.2021.pdf?language_id=1
https://www.bruegel.org/policy-brief/european-union-gas-survival-plan-2023