Não informado. (1959). Copper abstracts. Copper Development Association.
Chicago (17e ed.) BronvermeldingNão informado. Copper Abstracts. London: Copper Development Association, 1959.
MLA (8e ed.) BronvermeldingNão informado. Copper Abstracts. Copper Development Association, 1959.
Let op: Deze citaties zijn niet altijd 100% accuraat.