https://www.ips-journal.eu/topics/democracy-and-society/the-berlin-blob-7462/
https://euobserver.com/nordic/138868
https://www.opendemocracy.net/en/dark-money-investigations/laws-protecting-britains-democracy-from-big-money-are-broken/
https://www.ceps.eu/wp-content/uploads/2013/02/1304.pdf