
https://www.europarl.europa.eu/RegData/etudes/IDAN/2021/699811/IPOL_IDA%282021%29699811_EN.pdf

https://open.overheid.nl/documenten/ronl-48b77cf7bdf0f91d4ed394ca2a37d2041bc50647/pdf

http://ec.europa.eu/budget/mff/hlgor/library/reports-communication/hlgor-report_20170104.pdf