
https://www.lse.ac.uk/ideas/Assets/Documents/reports/LSE-IDEAS-The-Rise-of-Insurgent-Europeanism.pdf

https://blogs.lse.ac.uk/europpblog/2021/10/22/de-facto-differentiation-in-action-why-poland-will-stay-in-the-eu-with-or-without-the-blessing-of-brussels/

http://www.ips-journal.eu/regions/europe/article/show/free-spirits-2331/