Đế quốc Achaemenid ở Nam Á và các cuộc khai quật gần đây tại Akra phía Tây Bắc Pakistan bởi Peter Magee, Cameron Petrie, Robert Knox, Farid Khan, Ken Thomas tr.713
"Two Spartans of noble birth and great wealth, Sperthias son of Aneristus and Bulis son of Nicolaus, undertook of their own free will that they would make atonement to Xerxes for Darius' heralds who had been done to death at Sparta. Thereupon the Spartans sent these men to Media for execution." in LacusCurtius Herodotus Book VII: Chapter 134. This self-sacrifice occurred shortly after Darius' reign ended, when Xerxes was imminently to invade Greece in the Second Persian Invation. As Herodotus writes: "But to Athens and Sparta Xerxes sent no heralds to demand earth, and this was the reason: when Darius had before sent men with this same purpose, the demanders were cast at the one city into the Pit32 and at the other in case of a well, and bidden to carry thence earth and water to the king. For this cause Xerxes sent no demand. What calamity befel the Athenians for thus dealing with the heralds I cannot say, save that their land and their city was laid waste.."LacusCurtius Herodotus Book VII: Chapter 134.
“The size of the Persian Army”. Lưu trữ bản gốc ngày 17 tháng 9 năm 2017. Truy cập ngày 19 tháng 10 năm 2023.Quản lý CS1: bot: trạng thái URL ban đầu không rõ (liên kết) (Internet Archive)