https://www.boeckler.de/pdf/p_imk_report_125e_2017.pdf
http://www.iata.org/whatwedo/Documents/economics/impact_of_brexit.pdf
https://www.ilo.org/legacy/english/inwork/cb-policy-guide/declarationofPhiladelphia1944.pdf
http://www.economics-ejournal.org/economics/journalarticles/2017-10