http://blogs.lse.ac.uk/politicsandpolicy/john-mills-ge2017/
https://www.theguardian.com/politics/ng-interactive/2019/sep/02/a-typical-hour-in-the-life-of-the-irish-border?ncid=newsletter-ukThe%20Waugh%20Zone%20%20Mon%20Sept%202&utm_campaign=newsletter-The%20Waugh%20Zone%20%20Mon%20Sept%202
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/621848/60093_Cm9464_NSS_SDR_Web.pdf
https://blogs.lse.ac.uk/brexit/2021/02/04/indyref2-scottish-independence-would-be-2-3-times-more-costly-than-that-of-brexit-and-rejoining-the-eu-wouldnt-make-up-the-difference/