Não informado. (2018). Progressus: Engineering progress. Handelsblatt GmbH.
Chicago (17e ed.) BronvermeldingNão informado. Progressus: Engineering Progress. Dusseldorf, Alemanha: Handelsblatt GmbH, 2018.
MLA (8e ed.) BronvermeldingNão informado. Progressus: Engineering Progress. Handelsblatt GmbH, 2018.
Let op: Deze citaties zijn niet altijd 100% accuraat.