http://www.iata.org/whatwedo/Documents/economics/impact_of_brexit.pdf
https://www.strategie.gouv.fr/sites/strategie.gouv.fr/files/atoms/files/coe-rapport-travail-non-declare-fevrier-2019.pdf
https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/earningsandworkinghours/articles/contractsthatdonotguaranteeaminimumnumberofhours/may2017