Não informado. (1981). Direction of Trade Statistics. International Monetary Fund.
Chicagoスタイル(17版)引用形式Não informado. Direction of Trade Statistics. Washington: International Monetary Fund, 1981.
MLA(8版)引用形式Não informado. Direction of Trade Statistics. International Monetary Fund, 1981.
警告: この引用は必ずしも正確ではありません.