Não informado. (1970). Copper Abstracts. Copper Development Association.
Chicagoスタイル(17版)引用形式Não informado. Copper Abstracts. London: Copper Development Association, 1970.
MLA(8版)引用形式Não informado. Copper Abstracts. Copper Development Association, 1970.
警告: この引用は必ずしも正確ではありません.