
https://blogs.lse.ac.uk/europpblog/2023/10/17/why-differentiation-is-now-at-the-heart-of-europes-political-system/

https://blogs.lse.ac.uk/brexit/2018/10/30/after-brexit-the-uk-should-be-able-to-re-enter-the-eu-if-it-wishes-to-do-so/

https://www.ips-journal.eu/index.php?id=344&L=0&tx_news_pi1%5Bnews%5D=3399&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&cHash=f68cbd88e51ae918672017876e3f358f