Sources, in order of appearance:
Multiple sources
Encyclopedia Brittanica
Herodotus - The Histories
Herodotus
Tom Holland - Persian Fire: The First World Empire and the Battle for the West (Herodotus claimed that 4,000 Greeks were killed in the Battle of Thermopylae, with 300 of them being King Leonidas' Spartan troops. Modern estimates, though, have revised Herodotus' number.)
University of Texas
Professor Janice Siegel, Hampden-Sydney College
M.A. Dandamaev - A Political History of the Achaemeni Empire
Ehsan Yarshater - Encyclopaedia Iranica
Encyclopedia Brittanica
The Air University
Dandamaev
M.I.T.
