https://securingdemocracy.gmfus.org/wp-content/uploads/2020/08/ASD-Covert-Foreign-Money.pdf
https://www.lameduse.ch/2018/05/25/la-meduse-a-lu-affaire-gurtel-des-verdicts-qui-ebranlent-lespagne/
http://ftp.zew.de/pub/zew-docs/dp/dp20002.pdf
https://www.ipg-journal.de/rubriken/aussen-und-sicherheitspolitik/artikel/bruesseler-grossmachtphantasien-3891/