
https://www.ilo.org/wcmsp5/groups/public/—dgreports/—cabinet/documents/publication/wcms_662442.pdf

https://www.ipg-journal.de/regionen/global/artikel/detail/vorbei-mit-der-freiwilligkeit-4508/

http://www.acea.be/uploads/publications/ACEA_position_paper-Brexit.pdf