Não informado. Financial Times North Sea Letter and European Offshore News. Financial Times Business Information.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Financial Times North Sea Letter and European Offshore News. London: Financial Times Business Information.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Financial Times North Sea Letter and European Offshore News. Financial Times Business Information.
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