Não informado. (2019). Statistical Yearbook. United Nations, Department of International Economic.
Chicago-Zitierstil (17. Ausg.)Não informado. Statistical Yearbook. New York: United Nations, Department of International Economic, 2019.
MLA-Zitierstil (8. Ausg.)Não informado. Statistical Yearbook. United Nations, Department of International Economic, 2019.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.