Sastavljeno u Bruxellesu 11. veljače 2019.
Economic Impact of Export Restrictions on Raw Materials, offentliggjord 2010, s. 18, tillgänglig på http://www.oecd.org/publications/the-economic-impact-of-export-restrictions-on-raw-materials-9789264096448-en.htm, hämtad den 13 juli 2018.