The Index to International Statistics (IIS) covers the statistical publications of the international intergovernmental organizations (IGOs) such as the United Nations, European Community (EC), North Atlantic Treaty Organization (NATO), Organization for Economic Cooperation and Development (OECD), Organization of American States (OAS), Organization of Petroleum Exporting Countries (OPEC), and others. The index and the microfiche collection (covering most publications in the index from 1985 to the present) are housed at the Annex.