https://carnegieeurope.eu/2022/06/16/does-eu-need-treaty-change-pub-87330
http://upceo.ceo.gencat.cat/wsceop/6508/Resumen%20en%20espa%C3%B1ol%20-874.pdf
https://www.socialeurope.eu/sweden-achievements-uncertainty
https://blogs.lse.ac.uk/brexit/2021/02/04/indyref2-scottish-independence-would-be-2-3-times-more-costly-than-that-of-brexit-and-rejoining-the-eu-wouldnt-make-up-the-difference/