Babinger, Franz (1992). Mehmed the Conqueror and His Time. Princeton University Press. стр. 25. ISBN978-0-691-01078-6. „The combined host met Ottoman forces first on November 3, 1443, between the castle of Bolvan (near Aleksinac) and the city of Niš. Here Kasim Bey, then governor of Rumelia, Ishak Bey and other standard bearers were defeated”
Imber, Colin (2006). The Crusade of Varna, 1443—45. Aldershot ; Burlington (Vt.) : Ashgate, cop. стр. 16. ISBN978-0-7546-0144-9. OCLC470458159. Приступљено 1. 7. 2018. „In the course of their flight Kasim and Turahan burned all villages between Niš and Sofia.”
Imber, Colin (2006). The Crusade of Varna, 1443—45. Aldershot ; Burlington (Vt.) : Ashgate, cop. стр. 270. ISBN978-0-7546-0144-9. OCLC470458159. Приступљено 1. 7. 2018. „The Ottoman sources in general emphasize the disagreement and lack of cooperation between frontier Ottoman forces under Turakhan and sipahi army under Kasim”
Imber, Colin (2006). The Crusade of Varna, 1443—45. Aldershot ; Burlington (Vt.) : Ashgate, cop. стр. 16. ISBN978-0-7546-0144-9. OCLC470458159. Приступљено 1. 7. 2018. „In the course of their flight Kasim and Turahan burned all villages between Niš and Sofia.”
Imber, Colin (2006). The Crusade of Varna, 1443—45. Aldershot ; Burlington (Vt.) : Ashgate, cop. стр. 270. ISBN978-0-7546-0144-9. OCLC470458159. Приступљено 1. 7. 2018. „The Ottoman sources in general emphasize the disagreement and lack of cooperation between frontier Ottoman forces under Turakhan and sipahi army under Kasim”