Analysis of information sources in references of the Wikipedia article "Chagatai language" in English language version.
Chagatai Old Uzbek official.
Ebn Mohannā (Jamāl-al-Dīn, fl. early 8th/14th century, probably in Khorasan), for instance, characterized it as the purest of all Turkish languages (Doerfer, 1976, p. 243), and the khans of the Golden Horde (Radloff, 1870; Kurat; Bodrogligeti, 1962) and of the Crimea (Kurat), as well as the Kazan Tatars (Akhmetgaleeva; Yusupov), wrote in Chaghatay much of the time.