http://ukandeu.ac.uk/brexit-a-french-perspective/
https://www.instituteforgovernment.org.uk/sites/default/files/publications/IfG_Brexit_customs_WEB.pdf
https://onlinelibrary.wiley.com/doi/epdf/10.1111/jcms.13386
https://www.niauk.org/media-centre/blog/uk-explore-retaining-membership-euratom/