Não informado. (1944). Drilling contractor. American Association of Oilwell Drilling Contractors.
Chicago-Zitierstil (17. Ausg.)Não informado. Drilling Contractor. Dallas, Tex: American Association of Oilwell Drilling Contractors, 1944.
MLA-Zitierstil (8. Ausg.)Não informado. Drilling Contractor. American Association of Oilwell Drilling Contractors, 1944.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.