APA (7e ed.) Bronvermelding

Não informado. (1944). Drilling contractor. American Association of Oilwell Drilling Contractors.

Chicago (17e ed.) Bronvermelding

Não informado. Drilling Contractor. Dallas, Tex: American Association of Oilwell Drilling Contractors, 1944.

MLA (8e ed.) Bronvermelding

Não informado. Drilling Contractor. American Association of Oilwell Drilling Contractors, 1944.

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