
http://blogs.lse.ac.uk/brexit/2018/11/23/hubert-butler-essay-prize-what-happened-to-europe-without-frontiers/

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

http://www.ladocumentationfrancaise.fr/var/storage/rapports-publics/084000459.pdf