APA (7e ed.) Bronvermelding

Não informado. (1968). Annual Bulletin of Coal Statistics for Europe. United Nations, Economic Commission for Europe.

Chicago (17e ed.) Bronvermelding

Não informado. Annual Bulletin of Coal Statistics for Europe. New York: United Nations, Economic Commission for Europe, 1968.

MLA (8e ed.) Bronvermelding

Não informado. Annual Bulletin of Coal Statistics for Europe. United Nations, Economic Commission for Europe, 1968.

Let op: Deze citaties zijn niet altijd 100% accuraat.