Chuvash ( , ; , , ) is a Turkic language spoken in European Russia, primarily in the Chuvash Republic and adjacent areas. It is the only surviving member of the Oghur branch of Turkic languages, one of the two principal branches of the Turkic family. The writing system for the Chuvash language is based on the Cyrillic script, employing all of the letters used in the Russian alphabet and adding four letters of its own: Ӑ, Ӗ, Ҫ and Ӳ. Usage Chuvash is the native language of the Chuvash people and an official language of Chuvashia. It is spoken by 1,640,000 persons in Russia and another 34,000 in other countries. 86% of ethnic Chuvash and 8% of the people of other ethnicities living in Chuvashia claimed knowledge of Chuvash language during the 2002 census. Despite that and although Chuvash is taught at schools and sometimes used in the media, it is considered endangered, because Russian dominates in most spheres of life and few children learning the language are likely to become active users. A fairly significant production and publication of literature in Chuvash still continues. According to UNESCO's Index Translationum, at least 202 books translated from Chuvash were published in other languages (mostly Russian) since ca. 1979. However, as with most other languages of the former USSR, most of the translation activity took place before the dissolution of the USSR: out of the 202 translations, 170 books were published in the USSR and just 17, in the post-1991 Russia (mostly, in the 1990s). A similar situation takes place with the translation of books from other languages (mostly Russian) into Chuvash (the total of 175 titles published since ca. 1979, but just 18 of them in post-1991 Russia). History Chuvash is the most distinctive of the Turkic languages and cannot be understood by other Turkic speakers, whose languages have varying degrees of mutual intelligibility within their respective subgroups. Chuvash is classified, alongside several extinct languages including Bulgar, as the only remaining member of the Oghuric branch of the Turkic language family. Since the surviving literary records for the non-Chuvash members of Oghuric are scant, the exact position of Chuvash within the Oghuric family cannot be determined. The Oghuric branch is distinguished from the rest of the Turkic family (the Common Turkic languages) by two sound changes: r corresponding to Common Turkic z and l corresponding to Common Turkic š. The