
https://publications.parliament.uk/pa/cm201719/cmselect/cmbeis/379/379.pdf

http://ukandeu.ac.uk/wp-content/uploads/2018/10/The-mechanics-of-a-further-referendum-on-Brexit-Constitution-Unit-Report-1.pdf

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/665871/December_-_Joint_technical_note_on_the_comparison_of_EU-UK_positions_on_citizens__rights.pdf