21. He authored a series of Georgian dictionaries and influential works on the structure and history of Caucasian languages . 22. As a result, he became one of the premier experts of Caucasian languages to work in French. 23. Igor Diakonoff and others have suggested ties between the Hurro-Urartian languages and the Northeastern Caucasian languages . 24. Two-vowel systems are very rare worldwide, but are also found in some Northwest Caucasian languages . 25. Language families unique to this region are Northwest Caucasian languages , Northeast Caucasian languages and South Caucasian languages. 26. Language families unique to this region are Northwest Caucasian languages, Northeast Caucasian languages and South Caucasian languages. 27. Language families unique to this region are Northwest Caucasian languages, Northeast Caucasian languages and South Caucasian languages . 28. This case is found in Northeast Caucasian languages like ergative-case noun, marks the postessive case. 29. In Adyghe, like all Northwest Caucasian languages , morphology is the most important part of the grammar. 30. The Hittite language was a distinct member of the language isolate but may have been a Northwest Caucasian language .
