
https://trybunal.gov.pl/en/hearings/judgments/art/11662-ocena-zgodnosci-z-konstytucja-rp-wybranych-przepisow-traktatu-o-unii-europejskiej

https://www.consilium.europa.eu/media/ny3j24sm/much-more-than-a-market-report-by-enrico-letta.pdf

http://news.sky.com/story/theresa-may-theres-no-economic-case-for-breaking-up-the-uk-10787816