http://fedtrust.co.uk/views-from-the-federal-trust/free-movement-and-migration/
http://www.ecfr.eu/article/commentary_there_is_life_for_the_eu_after_brexit
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/680366/Technical_Note_-_International_Agreements_in_the_Implementation_Period_-_CLEAN.pdf
https://blogs.sussex.ac.uk/uktpo/2018/02/15/sustainability-impact-assessment-for-post-brexit-britain/