Here are some texts relevant to the period: (both ancient and modern sources listed
Burn, ARR. (1984) Persia and the Greeks, Duckworth, London.
Dandemaev, M.A. and Lukonin, V.G. (1989) The Culture and Social Institutions of Ancient Iran, Cambridge University Press, Cambridge.
Herodotos (1985) The Histories, trans. Rex Warner, Penguin, Harmondsworth.
Kuhrt, A. (1995) The Ancient Near East c. 3000-330BC Vol 2 Routledge, London.
Lawless and Cameron (1994) Studies in Ancient Persia, Thomas Nelson, South Melbourne. (This one is structured following the HSC syllabus, and is quite detailed)
Olmstead, A.T., (1948) History of the Persian Empire, University of Chicago Press, Chicago.
Roaf, M. (1990) Cultural Atlas of Mesopotamia and the Near East, Facts on File Ltd, New York.
Weishoefer, J. (1996) Ancient Persia 550BC-650 AD trans. Azodi, A. IB Tauris Publishing, London.
Study Guides that cover this option for the Society section, are also the Excel and the Macquarie guides (if you don't have these available to you, I can do a quick scan of my copies and email you the relevant pages, send me a PM if you would like me to do so.