https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1747en.pdf
http://The European Social Pillar – Towards An EU Minimum Wage Policy?
https://www.baua.de/DE/Angebote/Publikationen/Berichte/F2398.pdf?__blob=publicationFile&v=3
http://sprc.info/wp-content/uploads/2012/07/Polish-Migrants-in-London-extending-the-stay.pdf