https://publications.parliament.uk/pa/ld201719/ldselect/ldeucom/15/15.pdf
https://www.eda.admin.ch/dam/dea/fr/documents/folien/Folien-Abkommen_fr.pdf
http://www.ecfr.eu/page/-/Keeping_Europe_Safe_After_Brexit2.pdf
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/710147/DATA_-_FINAL.pdf