http://bruegel.org/wp-content/uploads/2017/03/WP_2017_03-.pdf
https://committees.parliament.uk/oralevidence/2766/pdf/
https://onlinelibrary.wiley.com/doi/epdf/10.1111/jcms.13386
https://institute.global/sites/default/files/articles/Fixing-the-Northern-Ireland-Protocol-A-Way-Forward.pdf