Não informado. (1944). Drilling contractor. American Association of Oilwell Drilling Contractors.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Drilling Contractor. Dallas, Tex: American Association of Oilwell Drilling Contractors, 1944.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Drilling Contractor. American Association of Oilwell Drilling Contractors, 1944.
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