Não informado. (1944). Drilling contractor. American Association of Oilwell Drilling Contractors.
Chicago-viite (17. p.)Não informado. Drilling Contractor. Dallas, Tex: American Association of Oilwell Drilling Contractors, 1944.
MLA-viite (8. p.)Não informado. Drilling Contractor. American Association of Oilwell Drilling Contractors, 1944.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.