http://voxeu.org/system/files/epublication/Brexit_Beckons_VoxEU.pdf
https://blogs.lse.ac.uk/brexit/2019/10/09/northern-ireland-depends-on-the-eus-fluid-borders-for-survival/
http://www.oliverwyman.com/content/dam/oliver-wyman/v2/publications/2018/march/Oliver-Wyman_Clifford-Chance-The-Red-Tape-Cost-of-Brexit.pdf
http://www.cesifo-group.de/ifoHome/publications/working-papers/CESifoWP/CESifoWPdetails?wp_num=6448&CESifoWP.search=+