https://www.icij.org/investigations/trafficking-inc/audits-aimed-at-flagging-labor-abuses-are-designed-to-fail-investigation-finds/
http://www.ilo.org/wcmsp5/groups/public/—dgreports/—dcomm/—publ/documents/publication/wcms_490959.pdf
http://www.nfuonline.com/assets/96747