https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/637748/Future_customs_arrangements_-_a_future_partnership_paper.pdf
https://www.bloomberg.com/news/articles/2017-08-25/brexit-bulletin-when-silence-isn-t-golden
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/728135/THE_FUTURE_UK-EU_RELATIONSHIP.pdf