Não informado. (1937). Concrete for railways. Portland Cement Association.
Chicago (17e ed.) BronvermeldingNão informado. Concrete for Railways. Chicago, Ill: Portland Cement Association, 1937.
MLA (8e ed.) BronvermeldingNão informado. Concrete for Railways. Portland Cement Association, 1937.
Let op: Deze citaties zijn niet altijd 100% accuraat.