
https://www.baua.de/DE/Angebote/Publikationen/Berichte/F2398.pdf?__blob=publicationFile&v=3

https://www.secours-catholique.org/sites/scinternet/files/publications/rapport_revenusans_contreparties.pdf

https://www.ilo.org/wcmsp5/groups/public/—ed_norm/—relconf/documents/meetingdocument/wcms_624037.pdf