Organization of Petroleum Exporting Countries. OPEC bulletin. Organization of the Petroleum Exporting Countries.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रOrganization of Petroleum Exporting Countries. OPEC Bulletin. Vienna, Austria: Organization of the Petroleum Exporting Countries.
एमएलए (9वां संस्करण) प्रशस्ति पत्रOrganization of Petroleum Exporting Countries. OPEC Bulletin. Organization of the Petroleum Exporting Countries.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.