
http://www.bertelsmann-stiftung.de/fileadmin/files/Projekte/Migration_fair_gestalten/IB_PolicyBrief_Einwanderungsgesetz_082017_ENG.pdf

https://www.opendemocracy.net/en/beyond-trafficking-and-slavery/exploitation-rule-not-exception/

http://www.cesifo-group.de/ifoHome/publications/working-papers/CESifoWP/CESifoWPdetails?wp_num=6460&CESifoWP.search=+