Berktay, Halil; Koulouri, Christina; Murgescu, Bogdan, eds. (2005). Ottoman Empire. Teaching modern southeast European history : alternative educational materials / series editor Christina Koulouri, Center for Democracy and Reconciliation in Southeast Europe, ISBN 9608685729, 9789608685727. Vol. 1. Center for Democracy and Reconciliation in Southeast Europe. p. 93. ISBN9789608685734. Retrieved 31 October 2019. Generally, in order to become a master (usta), one had first to be an apprentice (çirak) and then an aid (kalfa).
