Common Turkic s versus Oghuric l and Common Turkic z versus Oghuric r.

Siberian Turkic is split into a "Central Siberian Turkic" and "North Siberian Turkic" branch within the classification presented in Glottolog v4.8.

In other classification schemes (such as those of Alexander Samoylovich and Nikolay Baskakov), the internal classification is different.

References

Literature