Não informado. (1944). Drilling contractor. American Association of Oilwell Drilling Contractors.
Lua i Stíl Chicago (17ú heag.)Não informado. Drilling Contractor. Dallas, Tex: American Association of Oilwell Drilling Contractors, 1944.
Lua MLA (8ú heag.)Não informado. Drilling Contractor. American Association of Oilwell Drilling Contractors, 1944.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.