Beginning in 1983/84 published in 3 vols., with expansion to 6 vols. by 2007/2008: vol. 1--Organization descriptions and cross references; vol. 2--Geographic volume: international organization participation; vol. 3--Subject volume; vol. 4--Bibliography and resources; vol. 5--Statistics, visualizations and patterns; vol. 6--Who's who in international organizations. (From year to year some slight variations in naming of the volumes).

Yearbook of International Organizations is the most comprehensive reference resource and provides current details of international non-governmental (NGO) and intergovernmental organizations (IGO). Collected and documented by the Union of International Associations (UIA), detailed information on international organizations worldwide can be found here. Besides historical and organizational information, details on activities, events or publications, contact details, biographies of the leading individuals as well as the presentation of networks of organizations are included.