
https://www.gov.uk/government/news/programme-for-fourth-round-of-uk-eu-article-50-negotiations

http://blogs.lse.ac.uk/brexit/2017/12/05/a-high-risk-game-of-chicken-is-being-played-over-the-irish-border/

https://www.iod.com/Portals/0/PDFs/Campaigns%20and%20Reports/Europe%20and%20trade/IoD-Customising-Brexit.pdf?ver=2018-02-15-083137-800