^Hammarström, Harald; Forkel, Robert; Haspelmath, Martin; Bank, Sebastian (编). Kerek. Glottolog 2.7. Jena: Max Planck Institute for the Science of Human History. 2016.
Jack Ryalls, Susan J. Behrens,"Introduction to Speech Science--From basic theories to clinical application(言語科學概論--從基礎理論到臨床應用)"[1](页面存档备份,存于互联网档案馆),World Publishing; 1 edition (April 24, 2003),pp.167. ISBN 978-0205291007
Fortescue, Michael. 1998. Language Relations Across Bering Strait. London: Cassell & Co.
Comrie, Bernard. 1981, The Languages of the Soviet Union. Cambridge University Press.