
https://ukandeu.ac.uk/long-read/the-protocol-post-brexit-northern-ireland/?mc_cid=9de7c359e6&mc_eid=815b1928ec

https://www.nao.org.uk/wp-content/uploads/2017/07/The-Customs-Declaration-Service.pdf

https://www.instituteforgovernment.org.uk/sites/default/files/publications/IfG_Brexit_Euro_Court_Justice_WEB.pdf