An International Intergovernmental Organization (IGO) is just that; a coalition of foreign governments which work together to promote common ends. That can be humanitarian, political, economic, educational or social good. The biggest and oldest example is that of the United Nations; which was preceded by the League of Nations (after WWI). There are many dozens of these organizations now; several of the largest began within the UN but are now semi-autonomous (such as the World Bank, World Health Organization; and the International Monetary Fund)
The Honnold/Mudd library of the Claremont Colleges has a large collection of publications from the government of Great Britain. There are 17th century documents such as the Journals of the Huse of Lords (in Special Collections); Calendar of State Papers; Manuscript Collections; Hansard's Debates, and many others. The documents are not cataloged in the library catalog, Blais, except for some of the Indexes. Most of the collection is in paper and is housed on the first floow of the Mudd building in a temperature moderated area.
There are also documents on microcard, but these are being replaced by scanned online versions available from the British government at no cost. There are resources scattered around on microfilm, microfich, microcard and on CD-ROM. In general it is a difficult to use collection and requires the assistance of a librarian.
IN THE LIBRARY: Claremont has an extensive collection of documents from Intergovernmental Organizations (IGO's). Most of the documents are classified in LC classification order and shelved in the main library stacks. There are two collections of uncataloged items (pre-1970) IGO documents from a variety of organizations that are located in storage, and the League of Nations documents, that are shelved with the British government douments collection on Mudd One. Most can be located using the online catalog; Blais, and OCLC Worldcat for the others, then one must simply ask someone who might know.