http://sprc.info/wp-content/uploads/2012/07/Polish-Migrants-in-London-extending-the-stay.pdf
https://www.socialeurope.eu/2017/07/german-wages-need-rise/
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef18005en.pdf
http://blog.arbeit-wirtschaft.at/mindestlohn-zufriedenere-beschaeftigte/