The Red Book of the Peoples of the Russian Empire . (1993) · edited by Andrew Humphreys and Krista Mits · http://www.eki.ee/books/redbook

Atlas of the World’s Languages in Danger . Christopher Moseley (ed.) (2010) · UNESCO Publishing http://www.unesco.org/culture/en/endangeredlanguages/atlas

World Oral Literature Project . http://www.oralliterature.org

Encyclopedia of the World's Endangered Languages . Christopher Moseley (2007) · Routledge

Ethnologue: Languages of the World, 16th Edition (2009) . (2009) · edited by M. Paul Lewis · SIL International http://www.ethnologue.com/

The World Atlas of Language Structures . (2005) · edited by Bernard Comrie and David Gil and Martin Haspelmath and Matthew S. Dryer · Oxford University Press

Europe and North Asia ( pp. 211-282 ) . Tapani Salminen (2007) · In Encyclopedia of the World's Endangered Languages edited by C. Moseley · London & New York: Routledge

Endangered Languages Catalogue Project. Compiled by research teams at University of Hawai'i Mānoa and Institute for Language Information and Technology (LINGUIST List) at Eastern Michigan University . (2012) ·