APA

Organization of the Petroleum Exporting Countries O., . (1990). Official resolutions and press releases. Vienna, Austria: Organization of the Petroleum Exporting Countries, OPEC.

Chicago

Organization of the Petroleum Exporting Countries OPEC, . 1990. Official resolutions and press releases. Vienna, Austria: Organization of the Petroleum Exporting Countries, OPEC.

Harvard

Organization of the Petroleum Exporting Countries O., . (1990). Official resolutions and press releases. Vienna, Austria: Organization of the Petroleum Exporting Countries, OPEC.

MLA

Organization of the Petroleum Exporting Countries OPEC, . Official resolutions and press releases. Vienna, Austria: Organization of the Petroleum Exporting Countries, OPEC. 1990.