Libraries, Archives and Museums (به انگلیسی). Berlin, Boston: Walter deGruyter GmbH & Co KG. p. 273. ISBN 978-3-11-039586-0. Sheppard, Charles; Joubert
Matthias (eds.). Handbook of Comparative and Historical Indo-European Linguistics (به انگلیسی). Vol. 3. Walter deGruyter. p. 1843. ISBN 978-3-11-054243-1.
Scarecrow Press. p. 33. ISBN 978-0-8108-4237-3. Retrieved October 25, 2015. Nessa Wolfson; Joan Manes (1985). Language of Inequality. Walter deGruyter. p. 176
Gernot Windfuhr, "Persian Grammer: history and state of its study", Walter deGruyter, 1979. pg 4:""Tat- Persian spoken in the East Caucasus"" http://unstats