https://www.boeckler.de/pdf/p_wsi_report_39e_2018.pdf
http://ftp.iza.org/dp11249.pdf
http://www.acea.be/uploads/publications/ACEA_position_paper-Brexit.pdf
https://www.secours-catholique.org/sites/scinternet/files/publications/rapport_revenusans_contreparties.pdf