
http://www.ips-journal.eu/topics/european-union/article/show/say-it-with-feeling-2184/

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.ipg-journal.de/regionen/europa/artikel/detail/ein-bisschen-mehr-als-freundschaft-2458/