
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/650455/customs_bill_white_paper_print.pdf

https://www.cer.eu/sites/default/files/insight_SL_5.11.19_2.pdf

https://www.waz.de/politik/gabriel-brexit-vertrag-als-modell-fuer-eu-tuerkei-beziehung-id212938393.html