Não informado. Quarterly Bulletin of Coal Statistics for Europe. United Nations, Economic Commission for Europe, Coal Division.
Chicago (17e ed.) BronvermeldingNão informado. Quarterly Bulletin of Coal Statistics for Europe. Geneva, Suíça: United Nations, Economic Commission for Europe, Coal Division.
MLA (8e ed.) BronvermeldingNão informado. Quarterly Bulletin of Coal Statistics for Europe. United Nations, Economic Commission for Europe, Coal Division.
Let op: Deze citaties zijn niet altijd 100% accuraat.