Ivanov, Vyacheslav V., On the Relationship of Hattic to the Northwest Caucasian Languages, in B. B. Piotrovskij, Vyacheslav V. Ivanov and Vladislav G. Ardzinba, eds., Drevnyaya Anatoliya - Ancient Anatolia, Moscow: Nauka (1985) 26-59. In Russian with English summary.