https://www.ifs.org.uk/publications/10302
http://www.fdf.org.uk/news.aspx?article=7834
https://www.politico.eu/article/9-slippery-brexit-pledges/?utm_source=POLITICO.EU&utm_campaign=39a5c3d811-EMAIL_CAMPAIGN_2019_11_01_05_51&utm_medium=email&utm_term=0_10959edeb5-39a5c3d811-190380769
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/761852/05_December-_EU_Exit_Attorney_General_s_legal_advice_to_Cabinet_on_the_Withdrawal_Agreement_and_the_Protocol_on_Ireland-Northern_Ireland.pdf