《资治通鉴·唐纪·唐纪二十八》
刘子玄即刘知几，为避玄宗皇帝李隆基姓名的同音字而以字行于世。
子玄即知几也，避上嫌名，以字行。
Liu Zixuan, namely Liu Zhiji, adopted his courtesy name so as to avoid using the same character as the personal name of Emperor Xuanzong, Li Longji.