Não informado. (1974). Coal and Energy Quarterly. National Coal Board.
Chicagoスタイル(17版)引用形式Não informado. Coal and Energy Quarterly. London: National Coal Board, 1974.
MLA(8版)引用形式Não informado. Coal and Energy Quarterly. National Coal Board, 1974.
警告: この引用は必ずしも正確ではありません.