Harry Thurston Peck, Harpers Dictionary of Classical Antiquities (1898),"(Odrusai). The most powerful people in Thrace, dwelling in the plain of the Hebrus, whose king, Sitalces, in the time of the Peloponnesian War, exercised dominion over almost the whole of Thrace. (See Thracia.) The poets often use the adjective Odrysius in the general sense of Thracicus."
Herodotus, The Histories (ed. A. D. Godley),4.92.1,"XCII. From there, Darius set out and came to another river called Artescus, which flows through the country of the Odrysae; and having reached this river, he pointed out a spot to the army, and told every man to lay one stone as he passed in this spot that he pointed out. After his army did this, he led it away, leaving behind there great piles of stones."
Xenophon, Hellenica, 3.2.1, But when the Odrysians returned, they first buried their dead, drank a great deal of wine in their honour, and held a horse-race; and then, from that time on making common camp with the Greeks, they continued to plunder Bithynia and lay it waste with fire.
The Oxford Classical Dictionary by Simon Hornblower and Antony Spawforth, ISBN0-19-860641-9,"page 1515,"The Thracians were subdued by the Persians by 516"
The Oxford Classical Dictionary by Simon Hornblower and Antony Spawforth, ISBN0-19-860641-9, page1515,"Shortly afterwards the first King of the Odrysae, Teres attempted to carve an empire out of the territory occupied by the Thracian tribes (Thuc.2.29 and his sovereignty extended as far as the Euxine and the Hellespont)"
Readings in Greek History: Sources and Interpretations by D. Brendan Nagle and Stanley M. Burstein, ISBN0-19-517825-4, 2006, page230: "... , however, one of the Thracian tribes, the Odrysians, succeeded in unifying the Thracians and creating a powerful state ..."
The Oxford Classical Dictionary by Simon Hornblower and Antony Spawforth, ISBN0-19-860641-9, page1514, "the kingdom of the Odrysae the leading tribe of Thrace extented ver present-day Bulgaria, Turkish Thrace (east of the Hebrus) and Greece between the Hebrus and Strymon except for the coastal strip with its Greek cities"
Lysimachus: A Study in Early Hellenistic Kingship by Dr Helen S Lun, page19, "... Profiting from dynastic rivalries which had split the powerful Odrysian kingdom into three realms, in 341BC PhilipII finally ..."
The Oxford Classical Dictionary by Simon Hornblower and Antony Spawforth, ISBN0-19-860641-9, page1515, "Sitalces allied himself with the Athenians against the Macedonians"
The Peloponnesian War: A Military Study (Warfare and History) by J. F. Lazenby, 2003, page224, "... number of strongholds, and he made himself useful fighting 'the Thracians without a king' on behalf of the more Hellenized Thracian kings and their Greek neighbours (Nepos, Alc. ...
The History Of Rome by Livy, 2004, ISBN1-4191-6629-8, page 27: "... Pleuratus and Scerdilaedus might be included in the treaty. Attalus was king of Pergamum in Asia Minor; Pleuratus, king of the Thracians;