Organization of Petroleum Exporting Countries. OPEC bulletin. Organization of the Petroleum Exporting Countries.
Tohutoru Kātū Chicago (17th ed.)Organization of Petroleum Exporting Countries. OPEC Bulletin. Vienna, Austria: Organization of the Petroleum Exporting Countries.
Tohutoro MLA (9th ed.)Organization of Petroleum Exporting Countries. OPEC Bulletin. Organization of the Petroleum Exporting Countries.
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