https://s3.eu-central-1.amazonaws.com/euobs-media/59f9f4116a089cec71bf81b76413503a.pdf
https://www.consilium.europa.eu/media/ny3j24sm/much-more-than-a-market-report-by-enrico-letta.pdf
http://uk.reuters.com/article/us-britain-eu-negotiations-idUKKBN17R1XJ
https://www.foreignaffairs.com/europe/promise-and-peril-eu-expansion