Sedov, Valentin Vasilyevich (2013) [1995]. Славяне в раннем Средневековье [Sloveni u ranom srednjem veku (Slavs in Early Middle Ages)]. Novi Sad: Akademska knjiga. tr. 168, 444, 451. ISBN978-86-6263-026-1.
For a discussion of the treaty see O'Connell, Daniel P. (1967). State Succession in Municipal Law and International Law: Internal relations. 1. Cambridge, England: Cambridge University Press. tr. 213. ISBN978-0-521-05858-2.; for a copy of the treaty see British and Foreign State Papers, volume cxlv, page 1096.