https://www.gov.pl/web/primeminister/letter-from-prime-minister-mateusz-morawiecki-to-the-heads-of-governments-and-the-presidents-of-the-european-council-the-european-commission-and-the-european-parliament-on-relations-between-national-law-and-european-law
https://www.20minutes.fr/politique/2424043-20190115-non-traite-aix-chapelle-va-donner-alsace-lorraine-allemagne
http://www.ips-journal.eu/regions/europe/article/show/free-spirits-2331/