Organization of Petroleum Exporting Countries. OPEC bulletin. Organization of the Petroleum Exporting Countries.
Chicago-referens (17:e uppl.)Organization of Petroleum Exporting Countries. OPEC Bulletin. Vienna, Austria: Organization of the Petroleum Exporting Countries.
MLA-referens (9:e uppl.)Organization of Petroleum Exporting Countries. OPEC Bulletin. Organization of the Petroleum Exporting Countries.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.