organization of the petroleum exporting countries. (2017). annual report 2017. grasl druck & neue medien gmbh.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रorganization of the petroleum exporting countries. Annual Report 2017. austria: grasl druck & neue medien gmbh, 2017.
एमएलए (9वां संस्करण) प्रशस्ति पत्रorganization of the petroleum exporting countries. Annual Report 2017. grasl druck & neue medien gmbh, 2017.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.