Robert Hussey and Guldenpenning have proved this. For example, Socrates, in I.x, relates an anecdote which he had heard, and says that neither Eusebius nor any other author reports it, yet this anecdote is found in Sozomen, I.xxii, the similarity of diction showing that the text of Socrates was the source. The extent of this dependence cannot be accurately determined. Sozomen used the work of Socrates as a guide to sources and order. In some matters, such as in regard to the Novatians, Sozomen is entirely dependent on Socrates. But Sozomen did not simply copy Socrates. He went back to the principal sources used by Socrates and other sources, often including more from them than Socrates did. He used the writings of Eusebius, the first major Church historian. The Vita Constantini of Eusebius is expressly cited in the description of the vision of Constantine. Sozomen appears also to have consulted the Historia Athanasii and also the works of Athanasius including the Vita Antonii. He completes the statements of Socrates from the Apologia contra Arianos, lix, sqq., and copies Athanasius' Adv. episcopos AEgypti, xviii-xix. Rufinus is frequently used. Instructive in this respect is a comparison of Sozomen, Socrates, and Rufinus on the childhood of Athanasius. Rufinus is the original; Socrates expressly states that he follows Rufinus, while Sozomen knows Socrates' version, but is not satisfied with it and follows Rufinus more closely. The ecclesiastical records used by Sozomen are principally taken from Sabinus, to whom he continually refers. In this way he uses records of the synods from that of Tyre (335) to that of Antioch in Caria (367). For the period from Theodosius I, Sozomen stopped following the work of Socrates and followed Olympiodorus of Thebes, who was probably Sozomen's only secular source. A comparison with Zosimus, who also made use of Olympiodorus, seems to show that the whole ninth book of Sozomen, is mostly an abridged extract from Olympiodorus. Sozomen used many other authorities. These include sources relating to Christianity in Persia, monkish histories, the Vita Martini of Sulpicius Severus, the works of Hilarius, logoi of Eustathius of Antioch, the letter of Cyril of Jerusalem to Constantius concerning the miraculous vision of the cross, and Palladius. He also used oral tradition, adding some of the most distinctive value to his work. Publication The first printed (though untranslated) version of Sozomen, which was based on the Codex Regius of 1444,