https://www.baua.de/DE/Angebote/Publikationen/Berichte/F2398.pdf?__blob=publicationFile&v=3
https://www.ilo.org/wcmsp5/groups/public/—ed_protect/—protrav/—travail/documents/publication/wcms_862569.pdf
https://www.occrp.org/en/daily/17580-dr-congo-exposes-tens-of-thousands-of-ghost-workers-across-government-ministries