C. E. Bosworth, "Chorasmia ii. In Islamic times" in: Encyclopaedia Iranica (reference to Turkish scholar Kafesoğlu), v, p. 140, Online Edition: "The governors were often Turkish slave commanders of the Saljuqs; one of them was Anūštigin Ḡaṛčaʾī, whose son Qoṭb-al-Dīn Moḥammad began in 490/1097 what became in effect a hereditary and largely independent line of ḵǰᵛārazmšāhs." (LINK)
