https://www.socialeurope.eu/2017/05/irelands-brexit-borders-possible-solution/
https://www2.datainnovation.org/2021-aia-costs.pdf
https://static1.squarespace.com/static/56eddde762cd9413e151ac92/t/5ee543957ff72b39af3a76d6/1592083356837/Bloody+Well+Pay+Them+-+Peter+M.+Jaworski.pdf
https://eur-lex.europa.eu/eli/dir/2019/1152/oj