
https://socialeurope.eu/brexit-why-does-northern-ireland-matter-so-much

http://www.cesifo-group.de/ifoHome/publications/working-papers/CESifoWP/CESifoWPdetails?wp_num=6430&CESifoWP.search=+

http://www.cer.eu/sites/default/files/bulletin_118_js-sl_article2.pdf