http://www.europarl.europa.eu/RegData/etudes/IDAN/2017/599352/EPRS_IDA%282017%29599352_EN.pdf
https://www.socialeurope.eu/2017/06/britains-deepening-confusion/
https://blogs.lse.ac.uk/brexit/2021/02/26/future-british-european-security-relations-are-a-matter-of-trust/
https://publications.parliament.uk/pa/ld5801/ldselect/ldeucom/4/4.pdf