Não informado. (1930). International trade statistics. League of Nations.
Chicago (17e ed.) BronvermeldingNão informado. International Trade Statistics. Geneva, Suíça: League of Nations, 1930.
MLA (8e ed.) BronvermeldingNão informado. International Trade Statistics. League of Nations, 1930.
Let op: Deze citaties zijn niet altijd 100% accuraat.