"The UNESCO Thesaurus is a controlled and structured list of concepts used in subject analysis and retrieval of documents and publications in the fields of education, culture, natural sciences, social and human sciences, communication and information. Continuously enriched and updated, its multidisciplinary terminology reflects the evolution of UNESCO's programmes and activities. The first edition of the Thesaurus was released in English in 1977, with French and Spanish translations in 1983 and 1984. The second revised and restructured version was released in 1995. Today the Thesaurus is available in English, French, Russian and Spanish. Concepts are grouped into 7 broad subject areas which are broken down into microthesauri. The UNESCO Thesaurus is compliant with the ISO 25964 standard."