Sonyel, Salâhi Ramadan (1993). Minorities and the destruction of the Ottoman Empire. Turkish Historical Society Printing House. p. 61. ISBN975160544X. «Many of the women of the harem were non-Muslim, for example Sultana Kosem (Anastasia), of Greek origin, who was the wife of Ahmet I (1603-17), and the mother of Murat IV (1623-40), and of Ibrahim I (1640-8)».
