
http://blogs.lse.ac.uk/brexit/2018/05/15/switzerland-wanted-more-immigration-controls-but-economic-self-interest-will-probably-prevail/

https://ec.europa.eu/commission/publications/position-paper-essential-principles-citizens-rights_en

http://www2.warwick.ac.uk/fac/soc/pais/research/researchcentres/irs/crossingthemed/ctm_final_report_4may2017.pdf