https://www.nao.org.uk/wp-content/uploads/2017/07/The-Customs-Declaration-Service.pdf
https://www.esri.ie/system/files/publications/WP677_0.pdf
https://ukandeu.ac.uk/energy-security-and-industrial-strategy-uk-and-eu-divergence/
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/682894/Draft_Text_for_Discussion_-_Implementation_Period__1_.pdf