https://journals.sagepub.com/doi/pdf/10.1177/10242589211022550
https://eur-lex.europa.eu/legal-content/FR/TXT/PDF/?uri=CELEX:32019L2121&from=EN
https://www.socialeurope.eu/2017/07/german-wages-need-rise/
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1747en.pdf