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/
https://www.irishtimes.com/opinion/editorial/the-irish-times-view-on-brexit-day-britain-s-great-leap-backwards-1.4156666
https://journals.sagepub.com/doi/epub/10.1177/14651165231193830