Não informado. Quarterly Bulletin of Coal Statistics for Europe. United Nations, Economic Commission for Europe, Coal Division.
Chicago-Zitierstil (17. Ausg.)Não informado. Quarterly Bulletin of Coal Statistics for Europe. Geneva, Suíça: United Nations, Economic Commission for Europe, Coal Division.
MLA-Zitierstil (8. Ausg.)Não informado. Quarterly Bulletin of Coal Statistics for Europe. United Nations, Economic Commission for Europe, Coal Division.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.