Schmitt 2004, p. 588-590. Schmitt, Rüdiger (2004). «Hydarnes». In: Yarshater, Ehsan. Encyclopædia Iranica Vol. XII, Fasc. 6. Nova Iorque: Encyclopædia Iranica Foundation
Shahbazi 1994, p. 41–50. Shahbazi, Shapur (1994). «Darius I the Great». In: Yarshater, Ehsan. Encyclopædia Iranica Vol. VII. Nova Iorque: Encyclopædia Iranica Foundation