David Nicolle (2011 թ․ հուլիսի 22). «Devshirme System». In Alexander Mikaberidze (ed.). Conflict and Conquest in the Islamic World: A Historical Encyclopedia [2 volumes]: A Historical Encyclopedia. ABC-CLIO. էջեր 273–. ISBN978-1-59884-337-8. «This effectively enslaved some of the sultan's own non-Islamic subjects and was therefore illegal under Islamic law, which stipulated that conquered non-Muslims should be demilitarized and protected»