http://ec.europa.eu/epsc/sites/epsc/files/epsc_europe_is_back_trends_jan.pdf
https://www.ilo.org/legacy/english/inwork/cb-policy-guide/declarationofPhiladelphia1944.pdf
https://www.ips-journal.eu/index.php?id=340&L=0&tx_news_pi1%5Bnews%5D=4556&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&utm_source=newsletter&utm_medium=email&utm_campaign=en_808_20200804&cHash=1b8009a520c4886c5fb98c49979ef2c5
https://www.diw.de/documents/publikationen/73/diw_01.c.670904.de/19-31-3.pdf