Grousset, René. The Empire of the Steppes. Rutgers University Press, 1989, ISBN 0-8135-1304-9, p. 547. The Cambridge History of Iran: The Median and Achaemenian
Archiv für Orientforschung 46/47 (1999/2000:378-80); R. Rollinger, "The Median "empire", the end of Urartu and Cyrus' the Great campaign in 547 B.C. (Nabonidus
kingdom the many Iranian-speaking Median tribes" ( from Encyclopædia Britannica). D) "Proto-Iranian split into Western (Median, ancient Persian, and others)