Toynbee, Arnold (1973). Constantine Porphyrogenitus and His World (на језику: енглески). Oxford University Press. ISBN978-0-19-215253-4. Приступљено 10. 1. 2022. „A further settlement of 208,000 Slavs was planted in Bithynia (part, by then, of thema Opsikion), on the River … The earliest piece of evidence for a deportation of Slavs from the Balkan Peninsula to Asia Minor may be a seal inscribed … This seal is dated 'the eighth indiction', and this might be either the year 649/50 or the year 694/5. Since it is on record that 5,000 Slavs deserted from the East Romans to the Arabs as early as 664/5,1 Charanis dates the seal 650, and this dates the first deportation of Slavs from the Balkan Peninsula to Asia Minor in the reign of Constans II …”
Ninić, Ivan (1989). Migrations in Balkan History (на језику: енглески). Serbian Academy of Sciences and Arts, Institute for Balkan Studies. стр. 61. ISBN978-86-7179-006-2. Приступљено 10. 1. 2022.
Serbian Studies (на језику: енглески). North American Society for Serbian Studies. 1995. Приступљено 10. 1. 2022.
Cirkovic, Sima M. (2008). The Serbs (на језику: енглески). John Wiley & Sons. стр. 16—. ISBN978-1-4051-4291-5. Приступљено 10. 1. 2022.
Lemerle 1965, стр. 264, 270, 284.. Lemerle, Paul (1965). Thomas le Slave (на језику: француски). Ed. De Boccard. стр. 255—297. Приступљено 10. 1. 2022.